My daughter has my hand me down S2 and recently told me that she never used her workout app during cross country and track practices bc it takes forever to launch and set up and she got yelled at by the coaches. The S2 isn’t that old and shouldn’t be having issues like this already, esp with stock apps.
FWIW, at least for me, since watchOS 4.3, the workouts app is basically lag-free. It did lag in previous releases, not anymore.
(I have a few apps on the watch, but not many. I can't believe that there are all that many apps that are all that useful for such a small interface as the watch. It's a great notifications device, fitness tracker, alarm, timer, workouts aren't bad, maps directions prompts on the wrist is kind of cool, and it's useful to send a message in a pinch when you cannot get to your phone for some reason.)