Interesting. My Amiga with a 68030 @42Mhz could just about pull off mono 128Kbps decoding (as long as you didn't multitask too much). That would suggest the 486 was almost clock comparable to a 68030 at least for lossy decompression, perhaps the 486 was around ~110% had their been a 68030 series 80Mhz equivalent.
Yeah, I seem to remember there was that brief time period where my PC could barely play MP3s and I used to treat them like zip archives -- rendering them back out to WAV files to play them back.
I think you're right and that was around the 486 DX2, DX4, Pentium transitional time period.
I wonder if that was also an I/O limitation rather than just a CPU thing. Old floppies probably would not handle 128kbit. Hard drives were slow too, so was memory and bus.
I remember I could play 128kbit MP3s in full quality using mpg123 running under Windows for Workgroups 3.11 ONLY when I overclocked my 486DX4-100 to 120Mhz.
