Demaestro - 9:27 pm on Aug 26, 2010 (gmt 0)
TextPad has been really good to me, it has great syntax highlighting classes you can customize, and as mentioned it handles really large files quickly and with ease.
Even massive "find & replace" happens fast and hasn't crashed on me yet.
It has the coolest feature where you can highlight columns within text.
For example you can highlight the first 5 chars of a file all way down which is great if you have to insert or remove leading chars.