The only reason I didn't give it a zero star rating is that my level of expertise is pretty low. When I installed it, it locked down not only my main site, but four commercial sites installed on the same server. I had to go edit my .htaccess file to eliminate all mention of WebOptimizer.
Possible a good plugin, but should warn users not to enable unless they REALLY know what all those dozens of options mean, which quite honestly I don't.
So, install only if you know what you're doing. If not, stay well away from this baby, is my humble advice.