Slowdown

It seems that when i get really close to a textured object the Fps drop dramaticaly. Why is that?

Fillrate. The drawing of pixels becomes a bottleneck. This happens anytime a polygon takes up a large part of the screen (because you came very close.)

I understand , can i do something about it besides not getting to close? :)

is it a tiled texture? in my experineces of blitz 3d tiled textures, if tiled too much can cause a bad slow-down. try to use bigger textures maybe?

to decrease slow down i think you could lower your resolution, i think that might work, of your screen + textures