In my project I have a large c++ file with many includes. When I select the file in open documents window, cpu usage increases to 50% for about 30 seconds. But in 2.5.2 it takes less than one second.
Also it happens while/after edit the file. Same with all files, but not so noticeable.
If close Qt Creator during this time, the process continues to hang during those 30 sec.

The parsing time of the project is about 10 seconds if that matters. And it's the same in 2.5.2 and 2.6.0+.

I noticed this in version 2.6.0 and it still here in 2.7 beta.