Hi sOliver,

To be sure there are still issues to fix but we’ve also just done a new release that fixes the most important ones. We hope the wp-super-cache community will try it. Please be sure to turn compression off in wp-super-cache as that will prevent mod_pagespeed from rewriting the page. The HTML will be compressed downstream of mod_pagespeed by mod_deflate.

RE image-optimization in Apache — the cost will not be as high as I think you’re thinking. mod_pagespeed caches the rewritten images and only re-analyzes based on the origin TTL. So if you set your origin TTL at 1 day, then the behavior will be exactly you recommend.

We believe any of the speedups from mod_pagespeed being reported on the web are due to images. mod_pagespeed is not black magic: everything it does can be done manually; it’s just a lot easier to do it automatically.