When I open Atom, all is normal until I press Ctrl+D the first time. After that, everything from highlighting text to switching tabs is painfully slow.
I disabled all community packages, I’m on Windows 7, I have all Atom updates installed.
I created a CPU profile of switching tabs, you can view it using DevTools > Profiles > Load: https://gist.github.com/jscissr/7de0ed11d5b532d5f1ba
I hope this helps in finding the issue.