Jetbrains IDEs do a lot of indexing and caching so that operations that normally take a bit are faster. Full text search, find usages, identifying interface usage in duck types, etc.

But the killer feature for me is the refactoring tools. Changing a function signature, extracting an interface, moving code to new files or packages, etc. I pair with folks who use VS Code and its a bit tedious watching them use find and replace for renaming things.

I've never been able to benefit from an IDE in a way that make up for how much slower and more bloated they are.

That does sound legit if you have resource limitations. Thankfully I've always worked for corporations that hand out MacBook Pros like candy. Normal day for me is having two Jetbrains IDEs open with Chrome, Slack, Zoom, and a dozen containers. Still runs smooth.