What is Quick Look (QuickLookUIService) on Mac?
By Junaid, maker of Taskglass · Last reviewed
Makes file previews and thumbnails, like when you press Space on a file in Finder.
Quick Look is the macOS feature that previews a file when you press the Space bar and draws thumbnails of documents, photos and videos in Finder and Open dialogs. Several processes share the work: QuickLookUIService shows previews, while thumbnail and preview generators read the files in the background. They run on demand and go quiet when you stop browsing.
- Category
- macOS system
- Made by
- Apple
- Safe to quit:
- With care
Shown in Activity Monitor as QuickLookUIService, quicklookd, QLPreviewGenerationExtension, com.apple.quicklook.ThumbnailsAgent
Why is Quick Look (QuickLookUIService) using so much CPU or memory?
- Browsing folders with lots of photos, videos or PDFs that need thumbnails
- Previewing a very large or complex file
- A third-party Quick Look plug-in struggling with a file
What to do
- 1Wait for thumbnails to finish generating; it's a one-time cost per file
- 2Close the preview window or switch Finder to list view for huge folders
- 3Remove or update third-party Quick Look extensions you don't need
- 4Restart your Mac if it stays busy
Safe to quit? With care.
They relaunch when needed; an open preview will close.
Related processes
Part of the Taskglass Process Library