Laggy 3d Game: Custom texturing maybe?

I created a 3d-style game that loads textured blocks from an array. Each time the function that reads the array comes accross a ‘1’, it puts a 3d quad (6-sided cube) in its respective position and slaps a picture onto each side. its a huge array,

int glblocks[20][20]

and I am curious as to why every time I DONT look at any thing on my screen it runs fast, then if I turn the “camera” to anything texture mapped, It starts to get slow and laggy.

Why!?

BTW, while I got you thinking, is there any easier ways to load a 3d world? All I want is a way to get a reasonably good looking 3d environment that I can walk around in. That’s all.

Ack.

~Jesse

I would say that you are running out of texture memory on your videocard and so a part of textures is stored in the system memory, causing the slowdown.

-Lev