Beating high chimps boss runs in Legends is literally impossible

It is genuinely impossible to beat bosses when you have so much lag in the later stages. Currently in stage 15 and can't beat bloonarius because he crashes the game every time. Plus, not being able to sell during boss rushes is stupid because you sit there for up to 20 minutes waiting for the boss to reach the end while it lags the fuck out of your game, and IF you're LUCKY you don't crash, then you can win. IDK what they were thinking not letting us sell when they know shit gets laggy like crazy.