Hey friend, thanks for the feedback!
I will try to work on performance. Not that much has changed since the last demo, especially nothing related to CPU as opposed to GPU, but I'll look into it.
Raw stats are pretty powerful at first but they are tied to your intelligence stat. There's still a lot of balance left to do, crafting powerful spells is very important on higher-difficulty runs, but getting more gems becomes easier as you progress. I should adjust crafting costs for new players so they also get to craft cool effects even with limited gems.