Probably not much in the way of performance, but you're using almost 3 year old firmware, so any bugs or vulnerabilities such as the OpenSSL could still do with patching.
Just becareful, because you're on such an old version, you may need to upgrade and then do a full reset and re-apply your settings (not restore from old backup). There is a certain minimum version you need to be on to do a simple upgrade to the latest few releases. Have a quick check before you proceed