I think we're talking about two different things here...
Are you talking about in app pictures, such as what's posted on the timeline? Because I sometimes have to wait for a minute or two for them to actually load. This is not an android 4.3 issue, as its been happening for me for months.
If its a Google contacts Facebook picture you're talking about, then that's never ever EVER worked properly for some reason, and the user above who suggested haxsync is spot on, it works great.
sent from my GS3 running CM10.2
Sent from Galaxy SIII running CM