Thanks for the feedback and playing the game!
Huh, I actually never considered having rmb open the upgrades instead of lmb, that might be a good idea to implement. There's supposed to be a small deadzone distance where, even if you drag, the character won't move and will just open the upgrades, but I guess it wasn't big enough.
And I think the lag happens because of the unoptimised pathfinding haha
I added it last minute and didn't have much time to tweak it, I'll fix it in the next update.
Thanks again for the feedback!