I am using xfce with a minimal set of services and all the system apps and most others open instantly. Alt+tab is also always instant. It is an MS, Apple, Gnome/KDE problem, not modern computers one.
Absolutely, after using xfce for years I find windows very frustrating to use, to the point I can see my colleagues using it and I can see the lag they just think is normal.
Imagine if you work on computers for hours everyday what the cumulative impact is