Something I found in the AHI docs, seems more relevent to old amigas rather than Pegs, but hey I am desperate
I hope it give someone some ideas
thank you
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Q. Eeek! The song is playing veeeeeeery sloooooooowlly...@{ub}
A. Make sure the pitch is set to 100%. If it is, then you have hit the Amiga sound DMA barrier. If you're running in a PAL/NTSC screen then you must either set the maximum AHI frequency to 28KHz or reduce the mpeg samplerate to 1:2. You could also try running a VGA screen such as DBLPal if you have a multican or VGA/SVGA monitor.
If you have a graphics card, you must set the env-variable AUDIO56KHZ to 1 (only later versions of CyberGraphX4) or run C:AddAudioModes DBLSCAN. See the AHI guide for more details.