Haha, I love the “My IDE is so sluggish, it must be doing important stuff”.
It really isn’t. IntelliJ is just horribly laggish. VSCode, an electron (!) app with 100 plugins isn’t even that slow.
Imagine if it were the opposite, and moving the mouse or speaking into a microphone caused the compilation to fail in subtle ways. Well, background compilation/typechecking/whatever is messing with user interaction.