The SuperFX chip was an additional RISC processor includes in some Super Famicom cartridges to generate 3D graphics, the most famous example being the game Starfox.
However it's performance wasn't particularly impressive, with games on other 16 bit machines such as the Amiga demonstrating higher frame rates with similar levels of detail (e.g. the game No Second Prize).
What were the factors limiting the performance of the SuperFX chip for 3D graphics? Calculation speed, memory bandwidth, transfer speed when copying data to the Super Famicom for display?