DB sync can not keep with load balancer

Hello,

I have an issue, I currently have a Virtual server which members are two sites that I want to balance petitions between.

The balancing method I use is "least connections" the issue comes when the balancing method is to fast balancing and the DB can not keep up with it so I have discrepancies in the DB.

I am thinking in configuring the priority group option and put the site B as "fallback" but I believe that this will not work unless site A becomes unhabiable/down and will not add the node of site B if it site A gets crowded with petitions.

You guys have any light on how can I fix my issue?. 

Thanks in advance