This minify/gzip size effect is a well known quirk to developers of javascript minifiers. The minifier's symbol mangling algorithm often has a more pronounced effect than does advanced AST optimization.
This website has real life data on the matter for popular libraries:
Compare the trophies indicating smallest size for Minified versus Minzipped (gzip). Generally the smallest minified size yields the smallest minified+gzip size, but there are some notable anomolies outside the range of statistical noise. It is not practical for a javascript minifier to take a compression algorithm into account - it would blow up the minify timings exponentially.
This website has real life data on the matter for popular libraries:
* https://github.com/privatenumber/minification-benchmarks
Compare the trophies indicating smallest size for Minified versus Minzipped (gzip). Generally the smallest minified size yields the smallest minified+gzip size, but there are some notable anomolies outside the range of statistical noise. It is not practical for a javascript minifier to take a compression algorithm into account - it would blow up the minify timings exponentially.