Chronic issue for me. Consistently waiting on WebStorm lag to complete my typing/commands. May be the vim or other plugins I use, not sure. This is on 2 powerful machines. One Mac, one Windows.
Also try to disable any installed plugins if you have any. Some old markdown plugin were causing a stability problem on PhpStorm back then. You may have experiencing something similar.
One last suggestion: try to move/remove the folder that keeps your settings.
Not sure if any of these would help but may worth to try.