Ubershaders don't increase the average performance by any significant amount. What they do is get rid of lag spikes.
Your system should be powerful enough, so I wonder if there's something wrong with the settings... If you've turned up the enhancements, try turning them down again.
Also, please keep in mind that "Synchronous (Ubershaders)" lowers the performance a lot. If you're going to use ubershaders, the option you want is almost always "Asynchronous (Ubershaders)".
Your system should be powerful enough, so I wonder if there's something wrong with the settings... If you've turned up the enhancements, try turning them down again.
Also, please keep in mind that "Synchronous (Ubershaders)" lowers the performance a lot. If you're going to use ubershaders, the option you want is almost always "Asynchronous (Ubershaders)".