Resharper absolutely tanks my performance. Not only does it slow down cold start by ~5x, it introduces input lag on each keystroke. Back in VS2013, R# was indispensable, but with VS2017 the only feature I miss is namespace refactoring. It's also clunky how it gives you effectively two IDEs with two databases mushed into a single window.

I'm trying to wean myself onto VS code now (with vim keybindings), but being forced to stay in a single window is tough to swallow.