I think you are right, I had the LC III and Performa 630 specifically in mind. For some reason I remember they were 30Hz but everthing I find googling it suggest they were 66Hz (both video card and screen refresh).

That being said they were horrible on the eyes, and I think I only got comfortable when 100Hz+ CRT screens started being common. It is just that the threshold for comfort is higher than I remember it, which explains why I didn't feel any better in front of a CRT TV.