Uglify has actually gotten better the last few years, but Closure is still faster on multi-core machines. Here's Closure vs. Uglify on one of our apps: $

Uglify has actually gotten better the last few years, but Closure is still faster on multi-core machines. Here's Closure vs. Uglify on one of our apps: $ wc -c index.js | grep -v total 9320511 index.js $ cat index.js | time closure-compiler \ --warning_level quiet \ --third_party \ --jscomp_off es3 \ --compilation_level SIMPLE_OPTIMIZATIONS \ --language_in ECMASCRIPT5 > index.js.closure 2>/dev/null 33.54s user 0.93s system 369% cpu 9.336 total $ cat index.js | time closure-compiler \ --warning_level quiet \ --third_party \ --jscomp_off es3 \ --compilation_level ADVANCED_OPTIMIZATIONS \ --language_in ECMASCRIPT5 > index.js.closure-advanced 2>/dev/null 33.54s user 0.93s system 369% cpu 9.336 total $ cat index.js | time node_modules/.bin/uglifyjs \ --screw-ie8 --mangle --compress - > index.js.uglify 2>/dev/null 18.88s user 0.24s system 103% cpu 18.475 total $ wc -c index.js.*. | grep -v total 1750478 index.js.closure 1515331 index.js.closure-advanced 1763350 index.js.uglify $ gzip -9 index.js.* $ wc -c index.js*.gz | grep -v total 369749 index.js.closure-advanced.gz 397468 index.js.closure.gz 387896 index.js.uglify.gz This is Closure 20170218 (Oracle Java 8), uglify-js 2.4.19 (Node 6.8.1) on a quad-core MBP Pro 2015. Note the total times. Closure is heavily parallelized, and is twice as fast as uglify by using all 4 cores at almost 100% utilization. If you only have one core, though, Closure will be much slower. Of course, YMMV. It's true that Closure does a lot better if you use Google's Closure style, but it's not true that you have to. Without those tricks, Closure still produces code that's as compact as Uglify.