Howdy,
I think people got confused between "speed" (the original question) and "result".
It is probably true that Apostasy will get the person DF'd more often than a sex situation.
BUT I would contend that because a sex-matter is going to be more or less cut and dry and easier to resolve that the Elders would be faster to form a JC and get the matter to judgment much much faster than apostasy or some other matter.
With these other less "tangible" matters I think they are more likely to take their time in dealing with it. Especially if the issue is statements made, etc. that someone is saying are apostate or whatever. They would question the hearer, etc. before taking it to the JC. But once the JC was started it would probably be faster decision (assuming the apostasy was "proven") then a JC that discussed the ins and outs of sex.
--Eduardo