If you're not getting more out of IntelliJ than vim, then sure, vim will make you happier. But also then you're not getting from IntelliJ what it's trying to provide.
A GUI can be responsive and fast even when doing a lot of work behind the scenes. I'm perfectly fine with it taking it's time figuring out what argument I can use, or something else. But do not drop percieved responsiveness - I want to be able to type and/or click menus at all times.
I have an HP48 calc, even though it had a monstrous cpu for its time, the system had layers of interpretation rendering the UX well... sluggish. But the ergonomics and paradigm was so neat, that you didn't need real time. You could keep stacking functions on the HP48 stack, you'd know in advance how it would behave, so it wasn't an issue. And counter intuitively, I enjoyed the pauses so I could think about what to do next.
On a PC, the latency is both less predictable in occurrence and in how it is handled, so when a window is unexpectedly slow to appear, you have to notice and wait rather than continue to type, otherwise your input may be sent to the wrong window.