Advanced Closure Compiler vs. UglifyJS2
peterbe.com
peterbe.com
Apples and oranges comparison. Of course the technology that does more will be slower, especially when the 'more' requires a great deal of analysis on the input.
Note: I'm not saying closure compiler is better, I actually tend to think that it is not for most usages, as the language it compiles is 'pretty much but not really javascript', and the difference there makes it hard to add into an existing build process with confidence.
That was enough for the projects I'm thinking of to decide a relatively simple minifier like Uglify was a better choice for their specific situations. Now that a lot of pre-optimisation JS is the output from one transpiler or another, that might be more of a practical limitation.
https://github.com/google/closure-compiler/wiki/FAQ#closure-...