I've been looking into this problem, and it is common. But since there is a package for Mac with the same name, the solution for Mac users is hiding the solution for Linux users and our default sshfs.

This the best I got so far, from what actually works on Linux.

sshfs user@host:remoteDir localDir -o Ciphers=arcfour -oauto_cache,reconnect,no_readahead

note: this question was not appropriate for stackoverflow, dunno why: http://stackoverflow.com/questions/25365487/sshfs-too-slow-what-options-to-use-to-make-it-faster-not-for-mac-users