In general, Sublime Text 2 should be considerably faster now that it was in the early versions. Memory usage has been improved, less IO is done at startup, less CPU work is done at startup, more IO has been moved off the main thread, and important optimisations have landed in each beta. Only a handful of features have been introduced which incur a performance overhead (e.g., subpixel glyph positioning, indent guides), but it's a minimal overhead in each case.
Some plugins are known to cause severe performance issues. However, if you don't have any, it may be helpful to give more details on the kinds of performance issues you are seeing.