Sometimes I missing focus when typing

Hello guys,
Thanks a lot for your plug-in both creator and contributors.
I'm using OSX 10.11.5 (have used Yosemite as well).

The issue happens when I'm editing text in form or textarea – sometimes I loosing focus on field. This leads to sVim hotkeys got pressed instead of typing and mess begins. Unfocus happens randomly and start reproducing when I installed sVim.

I want to provide more info on that, but don't know where to grab logs.