Once you've listened at 2x speed for an extended period of time your brain adjusts to the higher speed, and 2x starts to feel limiting. There's a hard coded limit to the speed you can listen with the "Speed and Pitch" plugin to 2x speed both with and without pitch disentangled from speed.
This patch expands this limit to 4x, and adjusts the frequency window to be a little more, allowing for a "smoother" listen at high speeds. In addition the max/min limits are adjusted, and the limits move in smaller degrees (so you can get just that much closer to the speed you can psychologically handle when listening at high speed).
Ubuntu 20.04 focal
audacious:
Installed: 3.10.1-1build1
Candidate: 3.10.1-1build1
audacious-plugins:
Installed: 3.10.1-1build2
Candidate: 3.10.1-1build2
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: audacious-plugins 3.10.1-1build2
ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18
Uname: Linux 4.15.0-45-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Wed May 11 12:24:50 2022
InstallationDate: Installed on 2017-04-18 (1849 days ago)
InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: audacious-plugins
UpgradeStatus: Upgraded to focal on 2020-04-25 (746 days ago)
modified.conffile..etc.apport.crashdb.conf: [modified]
mtime.conffile..etc.apport.crashdb.conf: 2020-06-07T21:16:26.397404
looks like my patch is backwards, this should fix