No offense, but this is kinda a pointless question. Whether or not a course is “fast” is a function of both the course and the conditions on that day–which tend to vary. The course itself can be “fast” because of terrain (IMFL), road quality etc. or in the case of IMAUS or Roth because it’s short.
You can do statistical comparisons of actual race times but these are influenced by the depths of field in each race (Hawaii is faster for obvious reasons here. Euro races are deeper than NAS, etc…)
I found Providence 70.3 to be MUCH more challenging than Florida 70.3. The terrain on the two courses is nothing alike. The swim in Providence is faster due to a combination of salt water and being wetsuit legal, but the bike and run are much hillier. The run course in Providence features one beastly hill that you hit twice. Perhaps based on previous winning times these courses happen to fall 2nd and 3rd on the OP’s list, but in my mind, there is a huge chasm in difficulty between these two races.
The challenge in Florida 70.3 is managing the heat. Obviously, this challenge gets tougher as the day rolls on. In 2008, the pros got to run under an overcast sky and rain. The sun came out (along with 90+ degree temps) just in time for the MOPs and BOPs to get out on the largely unshaded run. Providence 70.3 has more ideal weather. However, this is coming from the perspective of someone who lives in the Northeast.
With that said, I think that every course has its challenges. What is
considered a challenge is all a matter of perspective, the strengths,
weaknesses, and training background that each athlete brings to that given
event. For this reason, I believe the list the OP created should be different for everyone.
To me the fastest course I know is Ironman WA which has a half ironman there aswell. it is the fastest course because conditions often are good, the ride and run is flat and the road is smooth. Ironman winning times have been around the 8hr mark. Also Ironman Australia is not short. Plus the world champion did the Ironman Australia Course in 8hrs 38mins
Florida in May is iffy because of the weather- you might or might not get hit with an early burst of summer weather. The long-running nickname for Gulf Coast in PCB is ‘Gulf Roast’ for a reason.
Well i wanted to do the Eagleman 70.3 Cambridge Marryland but is sold out
I am looking for a fast course and that race fitted best. Other suggestions in June/July