I found several streams playing in "slow motion" in most recent Wacup builds.
One example:
https://ice24.securenetsystems.net/WVCOServer info says:
Server: Icecast 2.4.0-kh8
Stream Name: Streaming by Securenet Systems Cirrus(R)
Content Type: audio/aacp
Bitrate: 32 kbps, Channels: 1
Samplerate: 44100 Hz
Metadata Interval: 16000
Version tested: 1.99.55.25130
Windows 10 Pro
Tried to play this stream with other player (web and Potplayer) and no issues, when played with Wacup, it was playing slooooow....
Originally found this stream from here:
https://www.radio.net/s/949thesurffmFinding stream which acts like this with Wacup is not easy but find atleast two so far.