I think also about the Draw Precision value issue, by default Quality Draw Precision = 0.5
This is too low if you are working in Class A with a single span surfaces / curves, as the previous post said try to increase the value if your computer works.
But take care about the value, if you check the maximum is 1 but after many investigations please remind about the "exponentiel" value from 0 to 1, also if you put 1 the most of the time 90% it works well... But sometime you will feel your model move slowly and block looks too big ! ! ! My recommendation is to put maximum 0.9 for a nice result.