A quality plugin, and very impressive. So much so that it got me into making a Firefox Community login to write this review (for the first time ever).

Performance is very good in realtime, though I've not tested this on older machines in terms of CPU cost.

Something very important needs to be mentioned for new users leaving bad reviews:

To get this working, you will need to RESTART Firefox, after closing all instances and threads ! At least under Firefox 103.0.2 Linux 64bit.

The perfect feature addition for the future (perhaps as a paid option) would be realtime "Normalisation" or "Compression"/"Limiting". Someone else mentioned wanting a higher amplification boost, and this would necessitate processing to stop audio-clipping.