Screen sharing has become very laggy recently

Screen sharing on my local networks (over Wifi) has become very laggy in the last week. This is on two different Wifi networks that I regularly use and connecting to a Mac Mini in one and an old MacBook Pro in another. Before this Screen sharing has been very responsive and pleasant to use. I have a feeling it got bad straight after the 10.7.4 upgrade.

I checked and it's already set to "Adapt quality to network conditions".

Is it worth trying to reset my preferences? Is it possible that it's trying to connect via the internet using BackToMac rather than using the LAN?