diff --git a/platform/core-api/src/com/intellij/openapi/startup/StartupActivity.java b/platform/core-api/src/com/intellij/openapi/startup/StartupActivity.java
index 9e2070a5366a..1cc576ceb532 100644
--- a/platform/core-api/src/com/intellij/openapi/startup/StartupActivity.java
+++ b/platform/core-api/src/com/intellij/openapi/startup/StartupActivity.java
@@ -32,9 +32,14 @@ public interface StartupActivity {
   ExtensionPointName<StartupActivity> POST_STARTUP_ACTIVITY = ExtensionPointName.create("com.intellij.postStartupActivity");
 
   /**
-   * Executed some time after startup on a background thread with no progress indicator. Such activities may produce notifications
-   * but should not be used for any work that needs to be otherwise visible to users. Such activities are run regardless
-   * of the current indexing mode and should not be used for any work that requires access to indices.
+   * Executed some time after startup on a background thread with no visible progress indicator. Such activities may produce
+   * notifications but should not be used for any work that needs to be otherwise visible to users (including work that consumes
+   * CPU over a noticeable period of time).
+   *
+   * Such activities are run regardless of the current indexing mode and should not be used for any work that requires access
+   * to indices. The current project may get disposed while the activity is running, and the activity may not be interrupted
+   * immediately when this happens, so if you need to access other components, you're responsible for doing this in a
+   * thread-safe way (e.g. by taking a read action to collect all the state you need).
    */
   ExtensionPointName<StartupActivity> BACKGROUND_POST_STARTUP_ACTIVITY = ExtensionPointName.create("com.intellij.backgroundPostStartupActivity");