I don't know which era of chip you're thinking of, but when I was a kid listening to MP3s, it was the late 90s, and I had a Performa 5200 with a 75 MHz PowerPC 603 (or possibly 603e); it had a FPU, like all PPC chips, and IIRC like the final series of 68k that Apple used, the 68040 which Wikipedia says was also used in some models of NeXT machine — my problem was MacOS and how it multitasked (cooperatively), making MP3 playback clip every few seconds if the player was in the background; and I'm sure it was the OS not the chip, because I later upgraded to a newer computer with a 200 MHz chip, and it behaved exactly the same way.