Thank you for playing! All of the bugs you've mentioned should be fixed in the latest patch, minus the crashes (which have hopefully been mitigated, but it's still something we've been looking into)
As for performance, the game will sometimes cache shaders and the like whenever they occur for the first time, causing some stuttering. That and the game being slightly CPU intensive can lead to slowdown on some hardware. We will be working on a custom caching/loader in the future, along with script optimizations, in order to maximize performance on all hardware! - Jeff