The 7.7s to process a 400KB page (Wikipedia) is particularly surprising. Assuming a processor that executes ~2 billion instructions a second, that's roughly 37,000 instructions executed for each byte of input, or a throughput of ~52KB/s. I wonder where all the time is being spent, as from my understanding minifiers just parse the input document and then write it out in some smaller canonical form.
Also, please, whenever you publish benchmarks, always include the specifications of the system they were performed on! 52KB/s may be horribly slow on a 3GHz i7 but pretty good for a 100MHz Pentium.
Note that "max" settings were used, meaning that, for example, both JS and CSS had to be minified (and that's delegated to UglifyJS2 and clean-css packages correspondingly).
Also, please, whenever you publish benchmarks, always include the specifications of the system they were performed on! 52KB/s may be horribly slow on a 3GHz i7 but pretty good for a 100MHz Pentium.