According to the transcript at https://fabiensanglard.net/another_world_polygons_SNES/
... I could get the software running again to run at about 30 frames per second if of course I'm using a fast cartridge because cartridges at the time you could buy them either 2.68Mhz [SlowROM] or 3.58Mhz [FastROM].
To give you an idea, the SNES actually runs a 3.6Mhz. It's a pretty fast chip for the time but the ROMs that run at that speed costs a little bit more that roms that run at a slower speed.
Using a 3.6Mhz ROM you know my dev kit can ran and go to run at 10Mhz so it was no problem for you just to set the switch to run to dev kit I got it running really fast frame rate so it's looking good ready. Then Fargo comes out he said "Can you use the slower ROM it'll save 50 cents a cartridge.".
(I recommend reading the whole thing, incidentally, it has a lot of very interesting detail.)
This is understandable; the fast ROM would make it easier to get a game running at the speed you want; the slow ROM would save money. Ideally you would use the slow ROM and decompress code and data into RAM as needed, but the machine only had 256K RAM total of which 64K each were earmarked for video and sound, leaving limited working space for decompression buffer, and the CPU was not very fast, limiting the sophistication of compression algorithms you could use.
Did any SNES games end up biting the bullet and paying extra for the fast ROM?