[cryzed]

Shouldn't be a problem as long as the parsed data in memory fits into the allocatable RAM size of the Python interpreter shipped with the 32bit Calibre version (4 GB theoretical limit, 2GB practical as far as I know) or the 64bit Calibre version (2^64 bytes, theoretically and practically unlimited). So... no, you won't ever encounter that problem -- it might slow some things down a tiny bit though, and make your configuration file very unreadable. The integrated (Scintilla?) Qt editor component might run into problems/slow-downs if it's just a huge line without any newlines. Well, just test it out for now, I would be really surprised if you encountered any actual problems.