Fastpath works fine with OpenACS. It only caches files under a certain size though.
I believe it takes effect in two cases.
1) Items under resources that are served directly out of the filesystem. This probably isn't a big deal because most of these items are cached on the client side anyway.
2) Any time ns_returnfile is called, such as when cr_write_content is called on filesystem stored content items. Most of these items are probably too big to be cached by fastpath.
So if you have large static files, it might be useful if you could configure squid to just cache those items. But as Andres said, you might want to use a different web server to handle those as well.
