Transmission seems to freeze when I add files >30GB, it freezes up for about 5 minutes, then adds the file and downloads from peers for another minute or two, then it'll just stop downloading altogether until force quit and restart. I can add another file (of any size) right after it unfreezes and it'll repeat this process (freeze, unfreeze, download, stop downloading) for each new file. But downloading will not continue until a restart of the application.
This only happens when I add a file >30GB in size and then add smaller files. It works perfectly fine when only small files are downloading. This behavior is observed with a watch folder in my case.
I took a sample of transmission from activity monitor while it was frozen, it is here: http://pastebin.com/WsW1vbua