There might be a memory leak, after a while the game filled all my 8GB memory and 1GB from the swap (on Linux). I played the game in Firefox.
Also here is where i got before my pc freeze (sry for the big resolution):
Woah that's amazing! I can't even past cave 5! Thanks for playing it, I'll check this memory leak issue. :)
I had an easy tactic: Get a +5 meter upgrade, and then buy everything you can EXCEPT for the +meters, and the reload shop upgrade. When the game becomes enough easy with all of your upgrades, then start buying EVERYTHING including the +meters, and the reload shops.