I agree with Sakura. You should definitely check out the "Chat Rps" as they are basically the same as Chatango chat based rp, except hosted here at Iwaku. Really it nothing at all to do with speed posting, just a different medium (Forum VS Chat). Fortunately we have some AWESOME GMs that run chat games here, unfortunately they don't do it often.
Forum RP is awesome, but yes, there is gonna be some waiting. Many of our members have jobs/school/social life which makes it difficult for them to reply on a multi-daily basis, or even a daily basis in some cases. Waiting 3 to 4 days between posts in group games is not uncommon in forum RP.
Again, CHAT RP! That is your ticket!
Also, If you are looking for partners for a FAST paced game put an interest check thread up specifying that!