sometimes the thighbraces cut off circulation if they are not adjusted just right. I had that problem in most of the older boats i had years ago. my legs would go to sleep withing the first 15minutes on the river, and it was definitely downright unpleasant.
the angle your legs are at in front of you is crucial. I like to be sort of 'bowed out' rather then straight up and down. I also have thick legs so the old wavesport and dagger thighbraces really cut into my legs. now my feet go numb much less often, mostly if i cinch myself in too tightly, like when i am poco nervous about the upcoming rapid. kind of a nevous habit. its almost better to be a little loose, and more comfortable, then locked in so tight that you lose circulation after 5 minutes.
two things i take for granted now,( i'm gonna have to apologize for starting the JK bandwagon thing going here but it's true... ) are the bean bag seat pad- 'the happy cheeks' and the simple thigh braces in Jackson boats. not saying it works for everyone but It has done me wonders. any type of seat pad can really help rolling too if one has a shorter torso as well. Some people slide insulite foam under their existing seatpad for a 1/4" lift.
so seat height combined with leg angle changes could help a lot. if all that doesnt work, maybe demo some other brands, to see if another boat feels better. For me the JK Superhero and Superstar are the best fitting and performing boats ive ever had, by lightyears.
one more thing i added , at least in my playboat, is the 'happy seat' thigh float bags. they lift your legs up and diminish the fatigue of hold your legs up in the thigh braces. its awesome. but it makes it harder to get out your boat , definitely a bit of a hazard. hope that input helps. good luck!