Do you want patches?  I'm testing putting 50 miners through this proxy and was running into stability issues.  I have mysql on a separate machine and am used to that being a bottleneck, so I looked into making it use persistent connections.  I am not familiar with the PDO extension, but found the instantiator in common.inc.php on line 31; I added array(PDO::ATTR_PERSISTENT => true) to the new call and this took care of my problems.

The whole line now looks like this:

return new PDO($BTC_PROXY['db_connection_string'], $BTC_PROXY['db_user'], $BTC_PROXY['db_password'], array(PDO::ATTR_PERSISTENT => true) );

I now have 32 connections from the proxy web server staying open (which is what I want).

Hopefully this helps someone.