Seems linked to refresh rate/gpu capability, yeah. RPGmaker doesn't like it. I did finish the game, and there were no more freezes. It doesn't mean the problem is 100% fixed, (it's not guaranteed to happen at any regular rate, so testing it's tough,) but so far no more trouble.
Viewing post in Bug Reports Thread - Release Version (0.5.0)
Just replying again to say I've finally gotten around to reading further on and testing the plugin. While I can't test if it's actually solving the problem, it sounds as though it did for you, and it's a fairly simple plugin that doesn't seem to be causing any NEW problems, so as of now it's included in the next release. I'll keep an eye out in case anything weird crops up.