Hi Uomo,
I can't think of many cases where you'd want to split the log files, as it could potentially make searching for information more difficult as you'd have to search into multiple files instead of just one. Then there's the question: "where do we cut-off"? Obviously, we wouldn't want to cut-off login right in the middle of a process, that would make things more confusing.
Also, if your file is higher than 10 mb and you can't email it to Support, they can create a FTP site for you to upload it. And for it to be slow in a text editor, it needs to be much larger than 10 mb, which is actually small for a log file. Trust me, I've seen MUCH bigger log files than this, and never had any real issues opening them in a text editor. In most cases, redoing a search in many different files will end up taking longer than loading a big file.
Regards,
Raphaël Lalonde-Lefebvre