IntelliJ is an IDE, though, not a text editor. If you want a text editor with AI, you may need to wait for Microsoft to bring ChatGPT to notepad.
It seems to be limited to a single CPU core at a time, so depending on your CPU boosting settings, some but not too much.
It's quite snappy despite not using a lot of resources. I tried replicating the effect using a CUDA-based alternative but I could get neither the snappiness nor the quality out of that.