I'm happy people want to.spend their time helping me, but it seems I was unclear about what kind of information I want.
First and formost I want to know not what DEs exists or which DEs are lightweight in general, but if any other DEs have something similar to the Activities view, where you see all open windows and can open new ones by typing.
Just in case that doesn't work out I want to know if other distros with GNOME and deb are more lightweight.
Thank you again, I really appreciate help!
@forteller Turning off all animations in GNOME might be your best solution, it makes everything feel much snappier.