Switching between files already open in another split causes interface lag.

If I:

• open a file in a qt creator code split,
• then add a new split window,
• open a c++ code file in this new split,
• then if I select this same file in the original split (through various means)
  qt creator will lag while all of the syntax highlighting turns off. It then seems to re-parse everything and when syntax highlighting returns I can interact with qt creator again (a few seconds).

This behavior can be repeated continually. I've been able to do it with at least 3 different methods of file switching: f4 cc/h switching, f2 following, and the file selector at the top of the split. The only way I haven't been able to get this to happen is by closing a file in a split to get the matching file to come up in the closed file's place. Doing this will not result in this bad behavior.