Are you aware that you can force VSYNC ON via your drivers?

Tearing usually occurs if you have low framerate and VSYNC off. If you switch VSYNC on, it will be replaced with stuttering and heavy mouse input lag (can be alleviated by selecting hardware mouse). 

You can get an optimal solution if you have GSYNC-compatible monitor and GFX card. In this mode, the framerate is variable and the monitor starts refreshing precisely the moment it receives a new frame. 

However, I doubt that the dev will be able to do anything about it, it's a performance-related problem, not an in-game bug.