OS X 10.9.3 Update causing coreservicesd lag I'm getting a lot of stalling and high CPU usage when I open folders in Finder for the first time after the 10.9.3 update. Opening that folder again works fine, but expanding a folder of 20-30 files or folders stalls the CPU on these processes for 30 seconds:


  coreservicesd
   com.apple.IconServicesAgent


I've tried relaunching Finder but the issue still occurs.
This is what fixed the problem for me:


Rebuild the Quicklook cache (in Terminal: qlmanage -r &amp;&amp; qlmanage -r cache)
Rebuild Spotlight index (sudo mdutil -E /)


I'm not exactly sure which one of those two really caused the problem. You can try them separately.
It takes a while to rebuild both the cache/index, but afterwards Finder worked as expected.