9

Apparently, uninstalling an app by dragging it to the bin may leave application leftovers in some folders (such as Library/Preferences/, Library/Applications Support/, Library/StartupItems/ etc...). Several sites explain how removing such leftovers can increase disk space.

However, I have no problem with storage. So, this is my question: apart from taking up disk space, do these application leftovers have any negative impact on performance?

10

Application preferences and caches will not have any impact on system performance, but if there are leftover startup daemons running, etc., there could absolutely be a performance penalty. There is no way to know for certain how much of an impact there could be. The best advice I can offer is to always check the application developer's uninstall guidelines. Some applications utilize uninstaller applications to ensure all the application support files are removed.

  • You can look for some app daemon leftover forgotten running with this command: launchctl list and it will show all running process, and all that did run at least once since the last boot but has terminated. Then look at their names for some older stuff you already deleted. – Prado Aug 29 at 3:27
  • Yes, using the app uninstaller is always a good idea, but unfortunately it's not guaranteed: some time ago I installed an Adobe app and after some days I uninstalled it using its uninstaller. Then, doing the research for posting this question today, I found a dozen of Adobe files and folders in my Library... – Gerardo Furtado Aug 29 at 5:04
  • Adobe Installs Apps & their uninstallers to Apps, but it also puts the various bits of its application manager [& attendant uninstallers] in utilities. That's why it's best to refer to the maker's guidelines. – Tetsujin Aug 29 at 6:22
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Files in the following subfolders of the root level /Library or User Library will not affect the performance of your Mac at all, as they will not be read or executed:

  • Application Support
  • Caches
  • Containers
  • Preferences

(Not an exhaustive list.)

Files in the following subfolders might affect performance as they may be loading or trying to load non-existent files:

  • StartupItems
  • Extensions
  • LaunchAgents
  • LaunchDaemons

(Again, not an exhaustive list.)

  • I doubt execution and reading of files under cache. I think OP didn’t specify about performance, but apps like Spotify feel faster if I delete cache. – ankii Aug 29 at 16:26
  • 1
    @ankiiiiiii We're talking about caches for apps that have been deleted. But generally, deleting caches should slow down performance until the cache has been recreated. – benwiggy Aug 30 at 7:26

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