I am not sure that it has anything to do with large files.
I can reproduce it also with relatively small files. Leave Textmate open, maybe let it rest for some time, in a different screen, then DO NOT SELECT IT by clicking. Just change screen so that you have now TM in front of you and scroll the windows with the track pad (do not click on the windows), then you should see that parts of the windows are not refreshed at all, sometimes it is just the pane with the line numbers, sometimes it is the text as well.
Maybe this can help other people reproduce the bug, including the developers and contributors. I posted a message on textmate-dev and I got it back through the digest, but I do not see it in the web interface.
Attached: two examples:
http://textmate.1073791.n5.nabble.com/file/t2991/refresh-1.png  http://textmate.1073791.n5.nabble.com/file/t2991/refresh-2.png 
-- Sent from: http://textmate.1073791.n5.nabble.com/textmate-users-f3.html