I thought so, too. I'm not interested enough to benchmark it, but for all practical purposes it's instantaneous on my machine. As fast to open a new terminal as it is to switch to the existing one.
Mine takes 50ms, assuming wsl is hot (recorded screen and compared mouse click frame to window pop up frame). I think op should try a different wsl distro or a blank machine and compare differences. I have on access scanning off, performance on, Ubuntu wsl distro, and windows 10.
