SVGA XServer vs framebuffer + X_FBDEV

[Alexei Khlebnikov]

I want to run linux on not-very-fast machine (Pentium-1 class, not-so-much
memory).
What configuration requires more resourses (mostly RAM, also CPU),
X_SVGA (or similar) server or framebuffer + X_FBDEV server ?
What configuration is lighter, faster?
I am interested mostly in 3.3.6 version, info about 4.x version also would
be helpful.