The best editor for large text files is hands down Notepad++ It has a multitude of options and plugins that ship with it and even more available to download. Most importantly it's freaking fast, and can handle everything I've thrown at it so far. I just opened a 25mb raw (.nef) file in less than half a second

I ran VS 2008 for about 18 months before I just couldn't handle it anymore. Over the course of that year 2008 got worse and worse; crashing, terrible memory leak, most importantly it just kept getting slower and slower and slower. It became so unbearable I wound up switching to notepad ++ to do most of my heavy lifting and coding for longer documents. I had the ability to switch about 3 months ago but decided to stick with 2008 for a few reasons, mostly just because I didn't want to have to re-do all my settings and set up tortoise svn again. Plus I had Dreamweaver cs5 and I had become quite fond of it. 2010 is so much better though. I swear the intellitype and autocomplete is better. Dreamweaver CS5 was great but I like VS 2010's layout and preference set up better. I also love being lazy and using the format option to clean up my messy code. I hope this helps.