This is what I've noticed too. Intellij has never exactly been speedy, but it had so many great features that it was worth it compared to other slow IDEs like Eclipse. And using a basic text editor like VIM or even VS Code with a big Java project isn't really feasible like it might be in other languages like Python or Node.

However, now it is really bogging down. I'm sure it doesn't help that I've got several IDEs open along with some monstrosity of a "microservice" framework running half a dozen docker services and DBs on an older Macbook Pro, but it's true that app and OS devs tend to use all increases in CPU and ram, and so absolute performance and battery life never seems to get better over the years, regardless of how much the underlying hardware itself has improved.