Sublime text 3 using massive amount of CPU on idle

It is due to the index files problem. Just disable that. This can be completely disabled by adding "index_files": false, to your Preferences.sublime-settings (Preference > Settings).

This seems to be caused by indexing:

https://github.com/SublimeTextIssues/Core/issues/537

https://www.sublimetext.com/blog/articles/file-indexing

Try adding

"index_files": false

in your configuration

Sublime text gives you an interface to check indexing status.

Go to Menu Help -> Indexing status.