There's no reason this should be happening on your local or live server. It does look like there may be a problem with one of our files (the K2 issue above). If you can make the change below, it should fix that first error:
In the /components/com_jfbconnect/libraries/profile.php file, at line 47, look for:
function jfbcProfilesOnRegister()
and change to:
function jfbcProfilesOnRegister($jUserId, $fbUserId)
With that fixed though, there's still no reason that JFBConnect, or anything else really, should be pushing your memory usage past 128MB per page. Are you changing any files or doing any sort of PHP development with JFBConnect, or otherwise on your site? I simply can't imagine what's going on. We run quite a few extensions on this site, and our normal memory usage per page is 28M, which can go much lower or slightly higher, but never above 40M.
Any information you can provide will help. Let us know if the above code fix changes anything, and we'll wrack our brains for other ideas.
Thanks,
Alex