diff --git a/scripts/startup/performance.py b/scripts/startup/performance.py
index c6fe58170..6d8f47b92 100644
--- a/scripts/startup/performance.py
+++ b/scripts/startup/performance.py
@@ -30,6 +30,8 @@ RESULT_PREFIX = "MOVIEPILOT_IMPORT_BASELINE="
 LIFECYCLE_RESULT_PREFIX = "MOVIEPILOT_LIFECYCLE_BASELINE="
 PERFORMANCE_FACTOR = 2.0
 PERFORMANCE_SLACK_MS = 500.0
+# 基线由维护者平台生成、CI 在 Linux runner 检查；给跨平台宽松预算保留小幅调度抖动带。
+PERFORMANCE_JITTER_FACTOR = 1.05
 
 
 def measure_import(target: str) -> dict[str, Any]:
@@ -311,7 +313,7 @@ def check_baseline(
         budget_ms = max(
             expected_target["max_ms"] * PERFORMANCE_FACTOR,
             expected_target["max_ms"] + PERFORMANCE_SLACK_MS,
-        )
+        ) * PERFORMANCE_JITTER_FACTOR
         if actual_target["median_ms"] > budget_ms:
             errors.append(
                 f"{target} 冷导入中位数 {actual_target['median_ms']}ms "
diff --git a/tests/test_architecture_baseline_cli.py b/tests/test_architecture_baseline_cli.py
index 098e6cf7d..395f16fea 100644
--- a/tests/test_architecture_baseline_cli.py
+++ b/tests/test_architecture_baseline_cli.py
@@ -636,6 +636,20 @@ def test_performance_check_ignores_environment_provenance_drift():
     assert startup_performance.check_baseline(expected, actual) == []
 
 
+def test_performance_check_keeps_small_cross_platform_jitter_margin():
+    """跨平台 runner 可使用 5% 抖动带，但超过最终预算仍必须失败。"""
+    expected = _performance_sample()
+    within_margin = _performance_sample()
+    within_margin["targets"]["app.factory"]["median_ms"] = 630.0
+    above_margin = _performance_sample()
+    above_margin["targets"]["app.factory"]["median_ms"] = 630.001
+
+    assert startup_performance.check_baseline(expected, within_margin) == []
+    assert startup_performance.check_baseline(expected, above_margin) == [
+        "app.factory 冷导入中位数 630.001ms 超过预算 630.0ms"
+    ]
+
+
 def test_performance_check_reports_lifecycle_component_replacement():
     """组件数量未变时，生命周期成员或顺序变化仍必须失败。"""
     expected = _performance_sample()