I once made the mistake of trying to edit a 50MB SQL file in Sublime Text. It took about 10 minutes to open. Once it had, every edit I made, every line I scrolled froze Sublime Text for another 2 to 3 minutes. I can only presume Sublime Text reads and renders the entire file at once, re-rendering on each edit, even if your window only shows 100 of the 10,000 lines. I love Sublime Text, however it is just impossible to use for large files. I suppose this is why we have stream editors like sed.