Why would you have decreased performance if switching algos? It's simply not the case and there is certainly no technical reason for that to happen.
The implementation itself has nothing to do with "somebody's" profit-switching algorithm. It just allows you to switch to a pool with a different algo without restarting the miner. Simply copying x13-mod of course will not work since it has 13 kernels and not 11.
I've experienced things like that, too (with sgminer in general not just this particular build) I sometimes cannot just restart the miner and get full hash rate. Rebooting the machine restores it. I can also predictably cut my hashrate in half by remotely accessing my Linux box through Teamviewer. Even after killing Teamviewer, the hashrate never recovers until I reboot, and I have Teamviewer daemon running all the time. There may be a memory leak that sgminer is unable to clear.