[Plugin: WP Super Cache] caching comments?

Hi, I found a trace of an old tweet about downloading a development version of supercache that caches comments. i have a high traffic site and the mysql processing required for the comments is just killing it. To make matters worse, I am using Paged Threaded comments, necessary to keep things remotely sane, but killing the server without caching.

Is comments caching still an option in some version of super cache, or does someone know of another plugin that might do this?