It depends on the water temperature and the distance. Some sprints are only 400 meters, some are 800. How well do you tolerate cold water? If you’re a good swimmer you may pick up about 10 seconds per 100 using a wetsuit. On the shorter races you will lose time in T1. If the distance is 600-800 meters you may have a slight advantage with a wetsuit. It all depends on how much faster you can swim and how fast you’re able to get out of it.
I don’t tolerate cold water very well so for me a wetsuit is almost a requirement since all my races are in Colorado and the water is usually colder than I like. When I visit my sister in Missouri I never use a wetsuit as the water there is much warmer.
A wetsuit is not a necessity. I have seen people swim just fine in water around 55 degrees or less. If the time factor is your only consideration I would say you could do just fine without a wetsuit. Unless you’re going to be contending for an age group placing a few seconds one way or the other is no big deal.
Don