Merge Request view causes firefox to freeze

I just upgraded gitlab from 6.8 to 7.5. When viewing a large merge request > 400 commits firefox becomes unresponsive and uses 100% of one core.

After awhile browser won't list all files "To preserve performance only X of Y>X files displayed" and commits "commits hidden to prevent performance issues"

I cannot reproduse this problem on chrome/chromium or opera.

Does anyone else have this issue, found workaround, solution?

Cheers D.