MacOS – How to keep QTKitServer (QuickLook Helper) CPU usage from exploding out of control? OR How to disable QuickLook entirely

findermacosquicklook

I've been watching lots of .MKVs lately, opened from the Finder. In Column View, when you single-click any file, QuickLook will load a viewable thumbnail into the next column over. This causes noticeable and repeated momentary hangs in Finder responsiveness.

I have a feeling this is related to a non-Apple-kosher file-type like Matroska Video giving QuickLook some problems.

Has anyone had experience with this problem, OR have a way to disable QuickLook entirely? I ask because I would rather have my OS always be responsive than have CPU time eaten so that a useless thumbnail can be loaded that I never use.

Best Answer

Open Terminal, type:

sudo nano /System/Library/Sandbox/Profiles/com.apple.qtkitserver.sb

This will open the nano editor with the rules file. Scroll right to the bottom of this file and enter:

(deny file-read* (regex #"^.*\.mkv$"))

After this do Ctrl-O and then Ctrl-X to save and exit the application.

Reference: http://forums.macrumors.com/showthread.php?t=1463364