I really like Quick Cache and use it on several of my sites but I'm getting a sense that's it's not supported anymore? Nobody seems to be responding to questions and Plugin website says this:
WP® Plugins (these are keepers)
These will soon graduate into official add-ons for s2Member®
(until then, you can download them here; we'll update your account once they graduate)
Please advise if it's time to start looking at other alternatives.