VS runs at 60fps, it's v-synced, so if you have a 75Hz monitor it runs at 75Hz. With 60Hz a frame has a duration of 16,6ms, so all smaller settings will still evaluate to 60fps. Using 32ms will cause 30fps and so on. Problem is all values get quantized, so if you use 24 fps sometimes you have 3 frames, sometimes you have 2 frames until next image, that's why videos at 24 fps are often stuttering on camera movement. Youtube for example uses 30fps (60fps now possible), to better fulfill the 60fps with even changes.