I see. Well this really depends on what type of RPs you'd be interested in, but as far as I know, here are a few that aren't extremely active, as in tons of posts a day, and are fairly good:
Pokemon: Legacy of the Dragon Islands
Arcanum
Atlantis Arising
The Shattered Era
There may be a few more, but these are the ones that come to mind at the moment. I also have an RP myself that isn't active in an everyday sense, as in only expect a post once at least every two weeks without dropping you, but I wouldn't want you to sign up for it if you are rather new to RPing, as it isn't exactly for new RPers as much If you are interested, here's the link:
http://www.pokecommunity.com/showthread.php?t=266816
There's also another RP, which speed I can't really tell you for certain, as it hasn't begun yet, but shows promise:
Uncharted Waters
Hope I helped.