Perhaps try tdewolff/minify?
I know I'm the author of https://github.com/tdewolff/minify, but while using MkDocs I wondered what this plugin was using. It came out as the fastest minifier by far (see https://github.com/privatenumber/minification-benchmarks) and may be useful if you want to compress more quickly. Just an idea, if there is no need you may close this issue of course :-)
Another issue with the current minifier (jsmin) is that it doesn't fully support ES6. I have scripts that minifies fine with tdewolff/minify but fails silently with this plugin. This is not mentioned anywhere, and with almost everyone supporting the thing, it is a good time to consider using an up-to-date JS minifier (which tdewolff/minify) does seem to be.
@byrnereese pinging for visibility.