I have a couple of suggestions regarding the interface:
1) When you hover over a button near the bottom of the screen, the bottom of the tool tip is often obscured by the Save/Export/Import bar. However, the bottom of the tool tip is where the most important information is: the price of the upgrade. I’d like it if, when you calculate the position of the tool tip, you check the position of the mouse pointer, but then also use a limit so that the tool tip doesn’t go past the edge of the viewable area.
2) Make it possible to disable the fade-in/fade-out effects, like the one that occurs when you click “View Perks”. It is painfully slow on my machine. You could eliminate this entirely, or disable it if Performance Bars is toggled.
I play on Firefox, if that makes a difference.