While I agree that you should always try searching from the most sepcific object you can, unfornuately, that is not always possible.
I turned in a support ticket for this and they acknoledged the issue and turned it over to their developers. In the example I gave to Smartbear support, I have 3 lines of code that used Sys.Findchild and these 3 lines took less than a second to complete in TC10 and are taking over 2 minutes to complete in TC11. I repeated the test multiple times in the exact same environment and TC10 was always less than a second and TC11 was always over 2 minutes. This is not an issue with my code, it is an issue with TC11.
Edit: I was running my tests using IE 11, Firefox 37 and Chrome 45. All of them took over 2 minutes when running the test in TC11. I see many other threads where people are having slowdowns in Chrome and made it sound like this is a Chrome only issue but in my experience this is a global TC11 issue.