intellij-sdk-code-samples/topics/reference_guide/performance/performance.md

IDE Perf plugin provides on-the-fly performance diagnostic tools, including a dedicated view for CachedValue metrics.

{type="tip"}

See also and

{type="note"}

Avoiding UI Freezes

Do not Perform Long Operations in UI Thread

In particular, don't traverse VFS, parse PSI, resolve references or query FileBasedIndex.

There are cases when the platform itself invokes such expensive code (e.g., resolve in AnAction.update()). We're trying to eliminate them. Meanwhile, you can try to speed up what you can in your plugin, it'll be beneficial anyway, as it'll also improve background highlighting performance.

WriteActions currently have to happen on UI thread, so to speed them up, you can try moving as much as possible out of write action into a preparation step which can be then invoked in background (e.g., using ReadAction.nonBlocking()).

Don't do anything expensive in event listeners. Ideally, you should only clear some caches. You can also schedule background processing of events, but be prepared that some new events might be delivered before your background processing starts, and thus the world might have changed by that moment or even in the middle of background processing. Consider using MergingUpdateQueue and ReadAction.nonBlocking() to mitigate these issues.

Massive batches of VFS events can be pre-processed in background, see AsyncFileListener (2019.2 or later).

Don't block EDT by long non-cancellable ReadActions in background threads

See General Threading Rules, especially its section on Read Action Cancellability.