CURL efficiency?

I make use of CURL to talk to a back-end system and I'm calling it several times per requested page and there are several page requests a second. Is there anything I can do to make this process more efficient? Does keep alive work? Do I need to keep the same connection handler and not close it after each request? Anyway to make CURL connections persistant like I can with MySQL and Memcache? Anything else that'd help? Thanks.