I don't use CLion, but I use Rider a lot. And at some point I had to modify their JVM settings and give it more RAM. It got much snappier. I think when there's not enough RAM for JVM it runs GC too much and it gets slow. I also don't really load the IDE all the time. It just always there, just sits open. I use it daily. No need to restart it. I admit it feels slower than some other apps, but not so slow really. I have a pretty dated Macbook Pro M1 and I would never characterize its performance as abysmal. "Could be faster" yes, but not abysmal by any measure.