In reply to Jeff Chandler.

Yep, minification is not something you can actually take lightly. There is a number of things that can -and will- break if you minify and concatenate files indiscriminately. That is why W3TC plugin has a lot of options, cause usually you will wreak havoc on any website by minifying and concatenating things. Unless you use twentyfourteen theme with almost no plugins, your site will be screwed.
The best minification option I found to work is just minify HTML files, carefully. At least, if you have a very huge website, your cached files will be 15-20 MB smaller :) Not a great deal.