perf: lazy-load MCP SDK and event types to reduce cold start by ~29% (#5584)

* perf: defer MCP SDK import by fixing import path in agent/core.py - Change 'from crewai.mcp import MCPServerConfig' to direct path 'from crewai.mcp.config import MCPServerConfig' to avoid triggering mcp/__init__.py which eagerly loads the full mcp SDK (~300-400ms) - Move MCPToolResolver import into get_mcp_tools() method body since it's only used at runtime, not in type annotations Saves ~200ms on 'import crewai' cold start. * perf: lazy-load heavy MCP imports in mcp/__init__.py MCPClient, MCPToolResolver, BaseTransport, and TransportType now use __getattr__ lazy loading. These pull in the full mcp SDK (~400ms) but are only needed at runtime when agents actually connect to MCP servers. Lightweight config and filter types remain eagerly imported. * perf: lazy-load all event type modules in events/__init__.py Previously only agent_events were lazy-loaded; all other event type modules (crew, flow, knowledge, llm, guardrail, logging, mcp, memory, reasoning, skill, task, tool_usage) were eagerly imported at package init time. Since events/__init__.py runs whenever ANY crewai.events.* submodule is accessed, this loaded ~12 Pydantic model modules unnecessarily. Now all event types use the same __getattr__ lazy-loading pattern, with TYPE_CHECKING imports preserved for IDE/type-checker support. Saves ~550ms on 'import crewai' cold start. * chore: remove UNKNOWN.egg-info from version control * fix: add MCPToolResolver to TYPE_CHECKING imports Fixes F821 (ruff) and name-defined (mypy) from lazy-loading the MCP import. The type annotation on _mcp_resolver needs the name available at type-check time. * fix: bump lxml to >=5.4.0 for GHSA-vfmq-68hx-4jfw lxml 5.3.2 has a known vulnerability. Bump to 5.4.0+ which includes the fix (libxml2 2.13.8). The previous <5.4.0 pin was for etree import issues that have since been resolved. * fix: bump exclude-newer to 2026-04-22 for lxml 6.1.0 resolution lxml 6.1.0 (GHSA fix) was released April 17 but the exclude-newer date was set to April 17, missing it by timestamp. Bump to April 22. * perf: add import time benchmark script scripts/benchmark_import_time.py measures import crewai cold start in fresh subprocesses. Supports --runs, --json (for CI), and --threshold (fail if median exceeds N seconds). The companion GitHub Action workflow needs to be pushed separately (requires workflow scope). * new action * Potential fix for pull request finding 'CodeQL / Workflow does not contain permissions' Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com> --------- Co-authored-by: Joao Moura <joaomdmoura@gmail.com> Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>
2026-07-01 05:08:12 +00:00 · 2026-04-22 02:17:33 -03:00
parent 160e25c1a9
commit 3be2fb65dc
8 changed files with 438 additions and 142 deletions
--- a/.github/workflows/import-time.yml
+++ b/.github/workflows/import-time.yml
@@ -0,0 +1,103 @@
+name: Import Time Guard
+
+on:
+  pull_request:
+    paths:
+      - "lib/crewai/src/**"
+      - "lib/crewai/pyproject.toml"
+      - "pyproject.toml"
+
+permissions:
+  contents: read
+
+jobs:
+  import-time:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.12"]
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: astral-sh/setup-uv@v6
+        with:
+          version: "0.11.3"
+          enable-cache: true
+
+      - name: Install the project
+        run: uv sync --all-extras --no-dev
+        env:
+          UV_PYTHON: ${{ matrix.python-version }}
+
+      - name: Benchmark PR branch
+        id: pr
+        run: |
+          result=$(uv run python scripts/benchmark_import_time.py --runs 5 --json)
+          echo "result=$result" >> "$GITHUB_OUTPUT"
+          echo "pr_median=$(echo $result | python3 -c 'import sys,json; print(json.load(sys.stdin)["median_s"])')" >> "$GITHUB_OUTPUT"
+          echo "### PR Branch Import Time" >> "$GITHUB_STEP_SUMMARY"
+          echo "$result" | python3 -c "
+          import sys, json
+          d = json.load(sys.stdin)
+          print(f'- Median: {d[\"median_s\"]}s')
+          print(f'- Mean: {d[\"mean_s\"]}s ± {d[\"stdev_s\"]}s')
+          print(f'- Range: {d[\"min_s\"]}s – {d[\"max_s\"]}s')
+          " >> "$GITHUB_STEP_SUMMARY"
+        env:
+          UV_PYTHON: ${{ matrix.python-version }}
+
+      - name: Checkout base branch
+        run: git checkout ${{ github.event.pull_request.base.sha }}
+
+      - name: Install base branch
+        run: uv sync --all-extras --no-dev
+        env:
+          UV_PYTHON: ${{ matrix.python-version }}
+
+      - name: Benchmark base branch
+        id: base
+        run: |
+          result=$(uv run python scripts/benchmark_import_time.py --runs 5 --json 2>/dev/null || echo '{"median_s": 0}')
+          echo "result=$result" >> "$GITHUB_OUTPUT"
+          echo "base_median=$(echo $result | python3 -c 'import sys,json; print(json.load(sys.stdin)["median_s"])')" >> "$GITHUB_OUTPUT"
+          echo "### Base Branch Import Time" >> "$GITHUB_STEP_SUMMARY"
+          echo "$result" | python3 -c "
+          import sys, json
+          d = json.load(sys.stdin)
+          if d.get('median_s', 0) > 0:
+              print(f'- Median: {d[\"median_s\"]}s')
+          else:
+              print('- Benchmark script not present on base branch (skip comparison)')
+          " >> "$GITHUB_STEP_SUMMARY"
+        env:
+          UV_PYTHON: ${{ matrix.python-version }}
+
+      - name: Compare and gate
+        run: |
+          pr_median=${{ steps.pr.outputs.pr_median }}
+          base_median=${{ steps.base.outputs.base_median }}
+
+          python3 -c "
+          pr = float('$pr_median')
+          base = float('$base_median')
+
+          if base <= 0:
+              print('⏭️  No base benchmark available — skipping comparison.')
+              exit(0)
+
+          change_pct = ((pr - base) / base) * 100
+          print(f'Base: {base:.3f}s')
+          print(f'PR:   {pr:.3f}s')
+          print(f'Change: {change_pct:+.1f}%')
+          print()
+
+          if change_pct > 5:
+              print(f'❌ BLOCKED: Import time regressed by {change_pct:.1f}% (threshold: 5%)')
+              exit(1)
+          elif change_pct > 0:
+              print(f'⚠️  Slight regression ({change_pct:.1f}%) but within 5% threshold.')
+          else:
+              print(f'✅ Import time improved by {abs(change_pct):.1f}%')
+          "
--- a/.gitignore
+++ b/.gitignore
@@ -30,3 +30,4 @@ chromadb-*.lock
 .crewai/memory
 blogs/*
 secrets/*
+UNKNOWN.egg-info/
--- a/lib/crewai-tools/pyproject.toml
+++ b/lib/crewai-tools/pyproject.toml
@@ -112,7 +112,7 @@ github = [
 ]
 rag = [
    "python-docx>=1.1.0",
-    "lxml>=5.3.0,<5.4.0",  # Pin to avoid etree import issues in 5.4.0
+    "lxml>=6.1.0,<7",  # 6.1.0+ required for GHSA-vfmq-68hx-4jfw (XXE in iterparse)
 ]
 xml = [
    "unstructured[local-inference, all-docs]>=0.17.2"
--- a/lib/crewai/src/crewai/agent/core.py
+++ b/lib/crewai/src/crewai/agent/core.py
@@ -78,8 +78,7 @@ from crewai.knowledge.knowledge import Knowledge
 from crewai.knowledge.source.base_knowledge_source import BaseKnowledgeSource
 from crewai.lite_agent_output import LiteAgentOutput
 from crewai.llms.base_llm import BaseLLM
-from crewai.mcp import MCPServerConfig
-from crewai.mcp.tool_resolver import MCPToolResolver
+from crewai.mcp.config import MCPServerConfig
 from crewai.rag.embeddings.types import EmbedderConfig
 from crewai.security.fingerprint import Fingerprint
 from crewai.skills.loader import activate_skill, discover_skills
@@ -119,6 +118,7 @@ if TYPE_CHECKING:

    from crewai.a2a.config import A2AClientConfig, A2AConfig, A2AServerConfig
    from crewai.agents.agent_builder.base_agent import PlatformAppOrAction
+    from crewai.mcp.tool_resolver import MCPToolResolver
    from crewai.task import Task
    from crewai.tools.base_tool import BaseTool
    from crewai.tools.structured_tool import CrewStructuredTool
@@ -1120,6 +1120,8 @@ class Agent(BaseAgent):
        Delegates to :class:`~crewai.mcp.tool_resolver.MCPToolResolver`.
        """
        self._cleanup_mcp_clients()
+        from crewai.mcp.tool_resolver import MCPToolResolver
+
        self._mcp_resolver = MCPToolResolver(agent=self, logger=self._logger)
        return self._mcp_resolver.resolve(mcps)

--- a/lib/crewai/src/crewai/events/init.py
+++ b/lib/crewai/src/crewai/events/init.py
@@ -6,112 +6,20 @@ This module provides the event infrastructure that allows users to:
 - Build custom logging and analytics
 - Extend CrewAI with custom event handlers
 - Declare handler dependencies for ordered execution
+
+Event type classes are lazy-loaded on first access to avoid importing
+~12 Pydantic model modules (and their transitive deps) at package init time.
 """

 from __future__ import annotations

+import importlib
 from typing import TYPE_CHECKING, Any

 from crewai.events.base_event_listener import BaseEventListener
 from crewai.events.depends import Depends
 from crewai.events.event_bus import crewai_event_bus
 from crewai.events.handler_graph import CircularDependencyError
-from crewai.events.types.crew_events import (
-    CrewKickoffCompletedEvent,
-    CrewKickoffFailedEvent,
-    CrewKickoffStartedEvent,
-    CrewTestCompletedEvent,
-    CrewTestFailedEvent,
-    CrewTestResultEvent,
-    CrewTestStartedEvent,
-    CrewTrainCompletedEvent,
-    CrewTrainFailedEvent,
-    CrewTrainStartedEvent,
-)
-from crewai.events.types.flow_events import (
-    FlowCreatedEvent,
-    FlowEvent,
-    FlowFinishedEvent,
-    FlowPlotEvent,
-    FlowStartedEvent,
-    HumanFeedbackReceivedEvent,
-    HumanFeedbackRequestedEvent,
-    MethodExecutionFailedEvent,
-    MethodExecutionFinishedEvent,
-    MethodExecutionStartedEvent,
-)
-from crewai.events.types.knowledge_events import (
-    KnowledgeQueryCompletedEvent,
-    KnowledgeQueryFailedEvent,
-    KnowledgeQueryStartedEvent,
-    KnowledgeRetrievalCompletedEvent,
-    KnowledgeRetrievalStartedEvent,
-    KnowledgeSearchQueryFailedEvent,
-)
-from crewai.events.types.llm_events import (
-    LLMCallCompletedEvent,
-    LLMCallFailedEvent,
-    LLMCallStartedEvent,
-    LLMStreamChunkEvent,
-)
-from crewai.events.types.llm_guardrail_events import (
-    LLMGuardrailCompletedEvent,
-    LLMGuardrailStartedEvent,
-)
-from crewai.events.types.logging_events import (
-    AgentLogsExecutionEvent,
-    AgentLogsStartedEvent,
-)
-from crewai.events.types.mcp_events import (
-    MCPConfigFetchFailedEvent,
-    MCPConnectionCompletedEvent,
-    MCPConnectionFailedEvent,
-    MCPConnectionStartedEvent,
-    MCPToolExecutionCompletedEvent,
-    MCPToolExecutionFailedEvent,
-    MCPToolExecutionStartedEvent,
-)
-from crewai.events.types.memory_events import (
-    MemoryQueryCompletedEvent,
-    MemoryQueryFailedEvent,
-    MemoryQueryStartedEvent,
-    MemoryRetrievalCompletedEvent,
-    MemoryRetrievalFailedEvent,
-    MemoryRetrievalStartedEvent,
-    MemorySaveCompletedEvent,
-    MemorySaveFailedEvent,
-    MemorySaveStartedEvent,
-)
-from crewai.events.types.reasoning_events import (
-    AgentReasoningCompletedEvent,
-    AgentReasoningFailedEvent,
-    AgentReasoningStartedEvent,
-    ReasoningEvent,
-)
-from crewai.events.types.skill_events import (
-    SkillActivatedEvent,
-    SkillDiscoveryCompletedEvent,
-    SkillDiscoveryStartedEvent,
-    SkillEvent,
-    SkillLoadFailedEvent,
-    SkillLoadedEvent,
-)
-from crewai.events.types.task_events import (
-    TaskCompletedEvent,
-    TaskEvaluationEvent,
-    TaskFailedEvent,
-    TaskStartedEvent,
-)
-from crewai.events.types.tool_usage_events import (
-    ToolExecutionErrorEvent,
-    ToolSelectionErrorEvent,
-    ToolUsageErrorEvent,
-    ToolUsageEvent,
-    ToolUsageFinishedEvent,
-    ToolUsageStartedEvent,
-    ToolValidateInputErrorEvent,
-)
-

 if TYPE_CHECKING:
    from crewai.events.types.agent_events import (
@@ -125,6 +33,223 @@ if TYPE_CHECKING:
        LiteAgentExecutionErrorEvent,
        LiteAgentExecutionStartedEvent,
    )
+    from crewai.events.types.crew_events import (
+        CrewKickoffCompletedEvent,
+        CrewKickoffFailedEvent,
+        CrewKickoffStartedEvent,
+        CrewTestCompletedEvent,
+        CrewTestFailedEvent,
+        CrewTestResultEvent,
+        CrewTestStartedEvent,
+        CrewTrainCompletedEvent,
+        CrewTrainFailedEvent,
+        CrewTrainStartedEvent,
+    )
+    from crewai.events.types.flow_events import (
+        FlowCreatedEvent,
+        FlowEvent,
+        FlowFinishedEvent,
+        FlowPlotEvent,
+        FlowStartedEvent,
+        HumanFeedbackReceivedEvent,
+        HumanFeedbackRequestedEvent,
+        MethodExecutionFailedEvent,
+        MethodExecutionFinishedEvent,
+        MethodExecutionStartedEvent,
+    )
+    from crewai.events.types.knowledge_events import (
+        KnowledgeQueryCompletedEvent,
+        KnowledgeQueryFailedEvent,
+        KnowledgeQueryStartedEvent,
+        KnowledgeRetrievalCompletedEvent,
+        KnowledgeRetrievalStartedEvent,
+        KnowledgeSearchQueryFailedEvent,
+    )
+    from crewai.events.types.llm_events import (
+        LLMCallCompletedEvent,
+        LLMCallFailedEvent,
+        LLMCallStartedEvent,
+        LLMStreamChunkEvent,
+    )
+    from crewai.events.types.llm_guardrail_events import (
+        LLMGuardrailCompletedEvent,
+        LLMGuardrailStartedEvent,
+    )
+    from crewai.events.types.logging_events import (
+        AgentLogsExecutionEvent,
+        AgentLogsStartedEvent,
+    )
+    from crewai.events.types.mcp_events import (
+        MCPConfigFetchFailedEvent,
+        MCPConnectionCompletedEvent,
+        MCPConnectionFailedEvent,
+        MCPConnectionStartedEvent,
+        MCPToolExecutionCompletedEvent,
+        MCPToolExecutionFailedEvent,
+        MCPToolExecutionStartedEvent,
+    )
+    from crewai.events.types.memory_events import (
+        MemoryQueryCompletedEvent,
+        MemoryQueryFailedEvent,
+        MemoryQueryStartedEvent,
+        MemoryRetrievalCompletedEvent,
+        MemoryRetrievalFailedEvent,
+        MemoryRetrievalStartedEvent,
+        MemorySaveCompletedEvent,
+        MemorySaveFailedEvent,
+        MemorySaveStartedEvent,
+    )
+    from crewai.events.types.reasoning_events import (
+        AgentReasoningCompletedEvent,
+        AgentReasoningFailedEvent,
+        AgentReasoningStartedEvent,
+        ReasoningEvent,
+    )
+    from crewai.events.types.skill_events import (
+        SkillActivatedEvent,
+        SkillDiscoveryCompletedEvent,
+        SkillDiscoveryStartedEvent,
+        SkillEvent,
+        SkillLoadFailedEvent,
+        SkillLoadedEvent,
+    )
+    from crewai.events.types.task_events import (
+        TaskCompletedEvent,
+        TaskEvaluationEvent,
+        TaskFailedEvent,
+        TaskStartedEvent,
+    )
+    from crewai.events.types.tool_usage_events import (
+        ToolExecutionErrorEvent,
+        ToolSelectionErrorEvent,
+        ToolUsageErrorEvent,
+        ToolUsageEvent,
+        ToolUsageFinishedEvent,
+        ToolUsageStartedEvent,
+        ToolValidateInputErrorEvent,
+    )
+
+# Map every event class name → its module path for lazy loading
+_LAZY_EVENT_MAPPING: dict[str, str] = {
+    # agent_events
+    "AgentEvaluationCompletedEvent": "crewai.events.types.agent_events",
+    "AgentEvaluationFailedEvent": "crewai.events.types.agent_events",
+    "AgentEvaluationStartedEvent": "crewai.events.types.agent_events",
+    "AgentExecutionCompletedEvent": "crewai.events.types.agent_events",
+    "AgentExecutionErrorEvent": "crewai.events.types.agent_events",
+    "AgentExecutionStartedEvent": "crewai.events.types.agent_events",
+    "LiteAgentExecutionCompletedEvent": "crewai.events.types.agent_events",
+    "LiteAgentExecutionErrorEvent": "crewai.events.types.agent_events",
+    "LiteAgentExecutionStartedEvent": "crewai.events.types.agent_events",
+    # crew_events
+    "CrewKickoffCompletedEvent": "crewai.events.types.crew_events",
+    "CrewKickoffFailedEvent": "crewai.events.types.crew_events",
+    "CrewKickoffStartedEvent": "crewai.events.types.crew_events",
+    "CrewTestCompletedEvent": "crewai.events.types.crew_events",
+    "CrewTestFailedEvent": "crewai.events.types.crew_events",
+    "CrewTestResultEvent": "crewai.events.types.crew_events",
+    "CrewTestStartedEvent": "crewai.events.types.crew_events",
+    "CrewTrainCompletedEvent": "crewai.events.types.crew_events",
+    "CrewTrainFailedEvent": "crewai.events.types.crew_events",
+    "CrewTrainStartedEvent": "crewai.events.types.crew_events",
+    # flow_events
+    "FlowCreatedEvent": "crewai.events.types.flow_events",
+    "FlowEvent": "crewai.events.types.flow_events",
+    "FlowFinishedEvent": "crewai.events.types.flow_events",
+    "FlowPlotEvent": "crewai.events.types.flow_events",
+    "FlowStartedEvent": "crewai.events.types.flow_events",
+    "HumanFeedbackReceivedEvent": "crewai.events.types.flow_events",
+    "HumanFeedbackRequestedEvent": "crewai.events.types.flow_events",
+    "MethodExecutionFailedEvent": "crewai.events.types.flow_events",
+    "MethodExecutionFinishedEvent": "crewai.events.types.flow_events",
+    "MethodExecutionStartedEvent": "crewai.events.types.flow_events",
+    # knowledge_events
+    "KnowledgeQueryCompletedEvent": "crewai.events.types.knowledge_events",
+    "KnowledgeQueryFailedEvent": "crewai.events.types.knowledge_events",
+    "KnowledgeQueryStartedEvent": "crewai.events.types.knowledge_events",
+    "KnowledgeRetrievalCompletedEvent": "crewai.events.types.knowledge_events",
+    "KnowledgeRetrievalStartedEvent": "crewai.events.types.knowledge_events",
+    "KnowledgeSearchQueryFailedEvent": "crewai.events.types.knowledge_events",
+    # llm_events
+    "LLMCallCompletedEvent": "crewai.events.types.llm_events",
+    "LLMCallFailedEvent": "crewai.events.types.llm_events",
+    "LLMCallStartedEvent": "crewai.events.types.llm_events",
+    "LLMStreamChunkEvent": "crewai.events.types.llm_events",
+    # llm_guardrail_events
+    "LLMGuardrailCompletedEvent": "crewai.events.types.llm_guardrail_events",
+    "LLMGuardrailStartedEvent": "crewai.events.types.llm_guardrail_events",
+    # logging_events
+    "AgentLogsExecutionEvent": "crewai.events.types.logging_events",
+    "AgentLogsStartedEvent": "crewai.events.types.logging_events",
+    # mcp_events
+    "MCPConfigFetchFailedEvent": "crewai.events.types.mcp_events",
+    "MCPConnectionCompletedEvent": "crewai.events.types.mcp_events",
+    "MCPConnectionFailedEvent": "crewai.events.types.mcp_events",
+    "MCPConnectionStartedEvent": "crewai.events.types.mcp_events",
+    "MCPToolExecutionCompletedEvent": "crewai.events.types.mcp_events",
+    "MCPToolExecutionFailedEvent": "crewai.events.types.mcp_events",
+    "MCPToolExecutionStartedEvent": "crewai.events.types.mcp_events",
+    # memory_events
+    "MemoryQueryCompletedEvent": "crewai.events.types.memory_events",
+    "MemoryQueryFailedEvent": "crewai.events.types.memory_events",
+    "MemoryQueryStartedEvent": "crewai.events.types.memory_events",
+    "MemoryRetrievalCompletedEvent": "crewai.events.types.memory_events",
+    "MemoryRetrievalFailedEvent": "crewai.events.types.memory_events",
+    "MemoryRetrievalStartedEvent": "crewai.events.types.memory_events",
+    "MemorySaveCompletedEvent": "crewai.events.types.memory_events",
+    "MemorySaveFailedEvent": "crewai.events.types.memory_events",
+    "MemorySaveStartedEvent": "crewai.events.types.memory_events",
+    # reasoning_events
+    "AgentReasoningCompletedEvent": "crewai.events.types.reasoning_events",
+    "AgentReasoningFailedEvent": "crewai.events.types.reasoning_events",
+    "AgentReasoningStartedEvent": "crewai.events.types.reasoning_events",
+    "ReasoningEvent": "crewai.events.types.reasoning_events",
+    # skill_events
+    "SkillActivatedEvent": "crewai.events.types.skill_events",
+    "SkillDiscoveryCompletedEvent": "crewai.events.types.skill_events",
+    "SkillDiscoveryStartedEvent": "crewai.events.types.skill_events",
+    "SkillEvent": "crewai.events.types.skill_events",
+    "SkillLoadFailedEvent": "crewai.events.types.skill_events",
+    "SkillLoadedEvent": "crewai.events.types.skill_events",
+    # task_events
+    "TaskCompletedEvent": "crewai.events.types.task_events",
+    "TaskEvaluationEvent": "crewai.events.types.task_events",
+    "TaskFailedEvent": "crewai.events.types.task_events",
+    "TaskStartedEvent": "crewai.events.types.task_events",
+    # tool_usage_events
+    "ToolExecutionErrorEvent": "crewai.events.types.tool_usage_events",
+    "ToolSelectionErrorEvent": "crewai.events.types.tool_usage_events",
+    "ToolUsageErrorEvent": "crewai.events.types.tool_usage_events",
+    "ToolUsageEvent": "crewai.events.types.tool_usage_events",
+    "ToolUsageFinishedEvent": "crewai.events.types.tool_usage_events",
+    "ToolUsageStartedEvent": "crewai.events.types.tool_usage_events",
+    "ToolValidateInputErrorEvent": "crewai.events.types.tool_usage_events",
+}
+
+_extension_exports: dict[str, Any] = {}
+
+
+def __getattr__(name: str) -> Any:
+    """Lazy import for event types and registered extensions."""
+    if name in _LAZY_EVENT_MAPPING:
+        module_path = _LAZY_EVENT_MAPPING[name]
+        module = importlib.import_module(module_path)
+        val = getattr(module, name)
+        globals()[name] = val  # cache for subsequent access
+        return val
+
+    if name in _extension_exports:
+        value = _extension_exports[name]
+        if isinstance(value, str):
+            module_path, _, attr_name = value.rpartition(".")
+            if module_path:
+                module = importlib.import_module(module_path)
+                return getattr(module, attr_name)
+            return importlib.import_module(value)
+        return value
+
+    msg = f"module {__name__!r} has no attribute {name!r}"
+    raise AttributeError(msg)


 __all__ = [
@@ -214,42 +339,3 @@ __all__ = [
    "_extension_exports",
    "crewai_event_bus",
 ]
-
-_AGENT_EVENT_MAPPING = {
-    "AgentEvaluationCompletedEvent": "crewai.events.types.agent_events",
-    "AgentEvaluationFailedEvent": "crewai.events.types.agent_events",
-    "AgentEvaluationStartedEvent": "crewai.events.types.agent_events",
-    "AgentExecutionCompletedEvent": "crewai.events.types.agent_events",
-    "AgentExecutionErrorEvent": "crewai.events.types.agent_events",
-    "AgentExecutionStartedEvent": "crewai.events.types.agent_events",
-    "LiteAgentExecutionCompletedEvent": "crewai.events.types.agent_events",
-    "LiteAgentExecutionErrorEvent": "crewai.events.types.agent_events",
-    "LiteAgentExecutionStartedEvent": "crewai.events.types.agent_events",
-}
-
-_extension_exports: dict[str, Any] = {}
-
-
-def __getattr__(name: str) -> Any:
-    """Lazy import for agent events and registered extensions."""
-    if name in _AGENT_EVENT_MAPPING:
-        import importlib
-
-        module_path = _AGENT_EVENT_MAPPING[name]
-        module = importlib.import_module(module_path)
-        return getattr(module, name)
-
-    if name in _extension_exports:
-        import importlib
-
-        value = _extension_exports[name]
-        if isinstance(value, str):
-            module_path, _, attr_name = value.rpartition(".")
-            if module_path:
-                module = importlib.import_module(module_path)
-                return getattr(module, attr_name)
-            return importlib.import_module(value)
-        return value
-
-    msg = f"module {__name__!r} has no attribute {name!r}"
-    raise AttributeError(msg)
--- a/lib/crewai/src/crewai/mcp/init.py
+++ b/lib/crewai/src/crewai/mcp/init.py
@@ -2,9 +2,17 @@

 This module provides native MCP client functionality, allowing CrewAI agents
 to connect to any MCP-compliant server using various transport types.
+
+Heavy imports (MCPClient, MCPToolResolver, BaseTransport, TransportType) are
+lazy-loaded on first access to avoid pulling in the ``mcp`` SDK (~400ms)
+when only lightweight config/filter types are needed.
 """

-from crewai.mcp.client import MCPClient
+from __future__ import annotations
+
+import importlib
+from typing import TYPE_CHECKING, Any
+
 from crewai.mcp.config import (
    MCPServerConfig,
    MCPServerHTTP,
@@ -18,8 +26,28 @@ from crewai.mcp.filters import (
    create_dynamic_tool_filter,
    create_static_tool_filter,
 )
-from crewai.mcp.tool_resolver import MCPToolResolver
-from crewai.mcp.transports.base import BaseTransport, TransportType
+
+if TYPE_CHECKING:
+    from crewai.mcp.client import MCPClient
+    from crewai.mcp.tool_resolver import MCPToolResolver
+    from crewai.mcp.transports.base import BaseTransport, TransportType
+
+_LAZY: dict[str, tuple[str, str]] = {
+    "MCPClient": ("crewai.mcp.client", "MCPClient"),
+    "MCPToolResolver": ("crewai.mcp.tool_resolver", "MCPToolResolver"),
+    "BaseTransport": ("crewai.mcp.transports.base", "BaseTransport"),
+    "TransportType": ("crewai.mcp.transports.base", "TransportType"),
+}
+
+
+def __getattr__(name: str) -> Any:
+    if name in _LAZY:
+        mod_path, attr = _LAZY[name]
+        mod = importlib.import_module(mod_path)
+        val = getattr(mod, attr)
+        globals()[name] = val  # cache for subsequent access
+        return val
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")


 __all__ = [
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -164,7 +164,7 @@ info = "Commits must follow Conventional Commits 1.0.0."
 [tool.uv]
 # Pinned to include the security patch releases (authlib 1.6.11,
 # langchain-text-splitters 1.1.2) uploaded on 2026-04-16.
-exclude-newer = "2026-04-17"
+exclude-newer = "2026-04-22"

 # composio-core pins rich<14 but textual requires rich>=14.
 # onnxruntime 1.24+ dropped Python 3.10 wheels; cap it so qdrant[fastembed] resolves on 3.10.
--- a/scripts/benchmark_import_time.py
+++ b/scripts/benchmark_import_time.py
@@ -0,0 +1,76 @@
+#!/usr/bin/env python3
+"""Benchmark `import crewai` cold start time.
+
+Usage:
+    python scripts/benchmark_import_time.py [--runs N] [--json]
+
+Spawns a fresh Python subprocess for each run to ensure cold imports.
+Prints median, mean, min, max across all runs.
+With --json, outputs machine-readable results for CI.
+"""
+import argparse
+import json
+import statistics
+import subprocess
+import sys
+
+
+IMPORT_SCRIPT = "import time; t0 = time.perf_counter(); import crewai; print(time.perf_counter() - t0)"
+
+
+def measure_import(python: str = sys.executable) -> float:
+    """Run a single cold-import measurement in a subprocess."""
+    result = subprocess.run(
+        [python, "-c", IMPORT_SCRIPT],
+        capture_output=True,
+        text=True,
+        env={"PATH": "", "VIRTUAL_ENV": "", "PYTHONPATH": ""},
+        timeout=30,
+    )
+    if result.returncode != 0:
+        raise RuntimeError(f"Import failed: {result.stderr.strip()}")
+    return float(result.stdout.strip())
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Benchmark crewai import time")
+    parser.add_argument("--runs", type=int, default=5, help="Number of runs (default: 5)")
+    parser.add_argument("--json", action="store_true", help="Output JSON for CI")
+    parser.add_argument("--threshold", type=float, default=None,
+                        help="Fail if median exceeds this value (seconds)")
+    args = parser.parse_args()
+
+    times = []
+    for i in range(args.runs):
+        t = measure_import()
+        times.append(t)
+        if not args.json:
+            print(f"  Run {i + 1}: {t:.3f}s")
+
+    median = statistics.median(times)
+    mean = statistics.mean(times)
+    stdev = statistics.stdev(times) if len(times) > 1 else 0.0
+
+    result = {
+        "runs": args.runs,
+        "median_s": round(median, 3),
+        "mean_s": round(mean, 3),
+        "stdev_s": round(stdev, 3),
+        "min_s": round(min(times), 3),
+        "max_s": round(max(times), 3),
+    }
+
+    if args.json:
+        print(json.dumps(result))
+    else:
+        print(f"\n  Median: {median:.3f}s")
+        print(f"  Mean:   {mean:.3f}s ± {stdev:.3f}s")
+        print(f"  Range:  {min(times):.3f}s – {max(times):.3f}s")
+
+    if args.threshold and median > args.threshold:
+        print(f"\n  ❌ FAILED: median {median:.3f}s exceeds threshold {args.threshold:.3f}s")
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()