Hello notyca,
Thank you for trying our game and leaving helpful feedback. To address your concern, part of our game design was to allow the chain reactions from the proc chain make the player feel significantly more powerful as you got more upgrades. As such, the early game is necessarily slow and a little sluggish to make the late game power feel more worth it. I do have a potential idea to alleviate the problem: give the player a secondary on-cooldown large AOE ability that does minimal damage to make the first few levels faster, but not impact the later levels. However, I think that would be a core mechanics change, which is against the rules.
iamthatduck2