> In theory, most of the time scrolling is as fast as in text mode. However,
> the problem arises when dispoffset reaches to the limit, maxoffset. Then 
> every bit of the memory to be displayed should be copied to the start 
> address of the display memory. With text mode, this requires merely about 
> 4kB (80 * 25 * 2) of data copying, but with graphics mode, much larger 
> 80 * 400 bytes (32kB) of data copying, which makes the system a bit 
> slower and less responsive. 

Given that frame buffer memory access tends to be significantly slower
than regular memory access, it may make sense to re-render the text
into the new frame buffer location rather than do a frame-buffer to
frame-buffer copy.

P6 and later processors may also benefit from using MTRR's or other
hacks to set "appropriate" caching types for the frame buffer memory.

						- Bill