I've been experiencing the issue ever since I upgraded to 3176, and I've tried multiple things to mitigate it, without success. I've disabled plugins, removed all the plugins, etc.
Even after wiping out the
~/Library/Application Support/Sublime Text 3 it lagged and ran my CPU into 200-300% range. Main symptom was lag and very slow sidebar scroll.
I've noticed that fresh projects were working fine, but issue occurred every time I loaded a project created with previous version of ST3. Rebuilding the project and workspace files from scratch removed the issue, so I presume there's a problem with parsing the old project files properly.
Hope this helps others too.