[SDL] realtime problem

[Carlos Rodríguez]

hi, my name is Carlos and i have a curious problem

I'm developing a game with sdl, lua and opengl and i have a problem with
the usage of the cpu in windows XP

my game is a collection of models, when i dont see any model i have 42 
fps and 10% of cpu used,
this 42fps i read that is normal because the monitor is 85Hz / 2 = 42fps 
(the doublebuffer and the assyncronous blits, i dont know more 
explanation, but this is a secondary problem, someone know how to make 
more fps?).
ok, but my real problem is when i see all models i have 18 fps and the 
cpu is in 10% too,.

Why i can obtain more fps using more cpu?
How can break the limit of 42fps (refresh rate / 2)?
and perhaps this is more opengl-question: i only represent 1.440.000 
faces (triangles, not triangles-strip), with vertex-buffer, using all 
textures units. Can i make better?, another extension to draw objects 
more quickly?

Thanks for your time and for this lib
Carlos

(and sorry for my school-english :P)