Textmate is my de-facto editor when working. It's very light on my Macbook resources while providing me with syntax highlighting for pretty much any language I've worked with. It loads very quickly when opening projects which allow getting into action faster. It does not pollute my projects with a ton of configuration files and I can launch it through the command line on whichever folder I am working on (I happen to be a big fan of the command line and actually don't mind editing files in VIM).

This is specially designed text editor for mac which has some amazing features as compared to others in this category.

TextMate is an excellent editor available for programmers, especially for Mac users. TextEditor is a very easy-to-use tool for viewing text, XML, CSV, and various other formats. It comes with line operations to convert text to upper or lower case, and the most impressive is the bundle feature that allows you to access the files per technology such as Hive, Java, HTML and the most common one, JSON