Could it be that you‘ve already been using the new GPU rendering in SublimeMerge but not ST3?
That would explain the visual corruption issues I sometimes have with Merge but not ST3. In Merge some actions, sometimes (mostly in the settings) corrupt the application window (sometimes also after minimizing and sleep) on my MacBook. To me it looked like a rendering/GPU issue. It looks like blocks of pixels having different colors, lines shifted, etc.
Yes we've been shipping the hardware accelerated rendering with Sublime Merge for some time now. A bug report would be welcome (Under Help > Report a Bug)
That would explain the visual corruption issues I sometimes have with Merge but not ST3. In Merge some actions, sometimes (mostly in the settings) corrupt the application window (sometimes also after minimizing and sleep) on my MacBook. To me it looked like a rendering/GPU issue. It looks like blocks of pixels having different colors, lines shifted, etc.