have you tried recoding to 64bit and see if it improves in same app/soft environment?
also another mp3 player would be a good thing to test

I don't think it is the mp3 player: I tested on mpg123, mp3blaster and mpxplay and I got the same result.
By 64bit you mean the bitrate?

I run JS/Linux in Chrome.
I am loading mpg123 with a test mp3 file. Mpg123 optimized for i386_nofpu.
unpack

1gzip -dc mpg123.test.tar.gz | tar xf -

run

1vmtime ./mpg123 -t cbr.mp3

A two-minute mp3 with 320 bitrate was decoded in 45 seconds. At 40 MIPS (estimated).

After all, you can check at home how long it takes for you to decode. It's not difficult.

One of two options here

1. Different sound card
2. Mess around with the FSB and/or ISA clock rate

I always wanted to test an original ssa/5 90 with a 1x multiplier and an 83mhz FSB

rmay635703 wrote on 2020-06-05, 02:26:

One of two options here […]
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One of two options here

1. Different sound card
2. Mess around with the FSB and/or ISA clock rate

I always wanted to test an original ssa/5 90 with a 1x multiplier and an 83mhz FSB

The ISA clock is likely generated by a clockgen chip which takes an input clock value from a crystal and outputs configurable clocks for FSB, PCI, and ISA. There is likely no BIOS option to set this, so you're looking at datasheets for the motherboard and potentially the clockgen.

I vote for another sound card. I hope the integrated one can by disabled in BIOS .

Who wants to bet the motherboard is by PC Chips/Amptron/Houston Tech/etc ?