Close your web browser or install "auto tab discard" plugin.
I can have Intellij, Firefix, and Chrome all open while typing in emacs and no typing pauses at all.
On the other hand, I can run Intellij alone with no other applications open, and still get pauses while typing.
It's an issue with Intellij itself, not a matter of system resources.
That said, at least for Java, I find the benefits outweigh the costs. But I don't find that to be true for any other language I use.
Close your web browser or install "auto tab discard" plugin.