Even coming from .NET/VS, I don't see why opening an editor was a big deal. You do it once day/week when using a big IDE. Having a quickly opening text editor matters more when editing one-off files. And a .NET workflow doesn't involve opening single files. You work on multiple projects in a Solution that you waiting for 20 seconds to open when you started your work week/day.
Ah, of course. Well in that case, I can see why Vim is a massive upgrade compared to what he was used too. Sort of reminds me of a time when I used Eclipse for a while, horribly slow editor that tonnes of people used to use (still used widely for Java development, specifically Android).
VS is really neat if you're doing C# dev, but yeah slow as heck to startup. It takes nearly a minute from a cold start on my windows dev machine, and 30s on warm start (has recently been closed). And this machine is a beast.