Come on guys! Just do some maths.
Our best guess is that the 3DS has a PICA200 running at 268MHz. This comes from the homebrew scene, so take it as you will.
It has two ARM11 CPUs each running at the same speed - 268MHz.
6MB of VRAM. 128MB of FCRAM.
Taken from the PICA200 wikipedia page:
pixel performance: 800 Mpixel/s
- 400 Mpixel/s @100 MHz
- 1600 Mpixel/s @400 MHz
vertex performance: 15.3 Mpolygon/s
- 40Mtriangle/s @100 MHz
- 160Mtriangle/s @400 MHz
100MHz is the bottom here. 268MHz / 100MHz = 2.68. That is our multiplier.
400 Mpixels/s * 2.68 = 1072 Mpixels/s.
40M Triangles/s * 2.68 = 107.2M Triangles/s.
Gamecube performance (from the Wikipedia. If you have a better source, share it):
648 Mpixels/s.
20M Triangles/s.
According to this data, the fillrate of the 3DS GPU is almost double, and the geometry capability is 5 times greater. This is all based on Wikipedia data though, so take it as you will.
GCN had 43MB of RAM.
24MB of it was system RAM.
3MB of it was VRAM.
16MB was used for the optical drive and other functions.
3DS has about 5x more system RAM, and twice as much VRAM.
Can't find much about ARM11 CPUs, so I'll end here.