They are typically lighter, but may not have as much "fancy" features such as GL-rendering and HW-compositing.
Basically don't bother if your main objective is for things to be "faster".
These are all about efficient and keyboard-driven UX.
my main objective isn't "faster", but one of my objectives is "not slower" :D
>I guess the performance impact of these WMs is smaller than with full blown desktop environments?
Yes, although with modern processors, GPUs and memory prices that is probably not an issue.
I use Xfce for a few years now, that's why I'm asking.
I used Xfce and switched to i3. I can't imagine going back whenever I'm in Linux. My work environment is MacOS and its frustrating having to manually move windows and like others have said is just plain clunky after having used a tiling window manager. It did take a bit of time to get used to i3, but once I did it was glorious.
I think I'll try them :)
I guess the performance impact of these WMs is smaller than with full blown desktop environments?