One of the reason why 2.4 console performance is good especially at low
bit depths is its ability to process more than 1 pixel per iteration and
its usage of mask arrays.  

I tried to generalize the above in cfbimgblt.c by incorporating the idea
in fbcon-cfb*.c. It's significantly faster but still not as fast as the
2.4 API. 

time cat /usr/src/linux/MAINTAINERs (40K text file) 
1024x768-8bpp, y-panning disabled 

2.5 old (with offscreen buffers) 

real    0m10.708s 
user    0m0.001s 
sys     0m10.707s 

2.5 new 

real    0m4.378s 
user    0m0.002s 
sys     0m4.375s 

2.4 

real    0m2.098s 
user    0m0.000s 
sys     0m2.070s 

I've only tested the implementation at 8, 16, 24, and 32 bpp.  24bpp is
slightly slower than 32 bpp :( 

Tony