I've never tried Fscreen (didn't know it existed) but do like fblit and ftext. Just having a few problems which I've mentioned elsewhere.
With Fblit you can use wbctrl to store icons into fastram. It helped free up a lot of my chip ram when I had lots of dawers open
I get the best speed when I use Blazewcp, Newwpa and Speedychip.
Instead of wbctrl you can try IconBeFast or if you are feeling brave PeterK's new icon.library.