I have about 900 pages on my site and a couple hundred posts, and about 100 of the pages had a redirect using this plugin. It was added a massive overhead for whatever reason my page load times, I disabled the plugin and it saved me 2-3 seconds on each page.
Not sure if its just because of the size of my site, I've had problems with other plugins because of that before. Other redirection plugins don't cause any problems.
Just a word of warning to some of you if you notice load times increasing.