I added an upper limit to the number of growths that can be displayed at once. This has highlighted that the issue seems to be that something isn't being cleaned up properly in the background, since even when it reaches a limit much lower than the 3000 I was seeing problems at, it eventually starts to lag like it had before. I'll need to investigate further.
I also re-added the health system for the growths. Now, when they are shot, they decrease in level until they hit zero and disappear. However, I think the pool I created is causing troubles with this, since the growths stop spawning after enough are shot, since they are being pulled out of the pool with zero health. This should be easy to fix.
There still might be something to this game, or maybe not. However, I at least want to get the bugs worked out before I call it "done." I have an idea that would use multiple avatars, but it could take advantage of all the work I've done already, so it makes sense to keep ironing out the issues.