If you click a frame in the Time Slider, the correct state of all dynamic objects in the scene is displayed only if Maya performs run-up to calculate each frame prior to that frame. Maya doesn’t perform run-up by default, so you need to turn it on if you want to click frames in the Time Slider. Note that run-up also occurs for hidden objects.
Leave run-up turned off if you want to prevent Maya from calculating dynamics when you click a frame in the Time Slider. This is useful in a scene that has both nondynamic objects and complex dynamic objects, where you want the state of nondynamic objects to appear promptly after you click the Time Slider. If you are keying dynamic objects, it’s also useful leave run-up turned off to avoid waiting for calculations that are irrelevant to your keying activities.
To turn on run-up for all dynamic objects
If you click a frame higher than the current frame, run-up starts from the prior current time and ends at the frame you click. Turn this option on if you won’t be changing any attributes of a dynamic object in the scene. This setting lessens the time you’ll spend waiting for run-up. If you click a frame lower than the current frame, run-up starts from the beginning of the animation.
Run-up starts from the start frame regardless of where you click in the Time Slider. Turn this option on if you plan to change any attributes of a dynamic object in the scene. This ensures that you see the correct object states when you click in the Time Slider after modifying an object’s dynamics.
Run-up always occurs in batch rendering. For instance, if you batch render frames 20 through 50, all particle effects will render correctly even if Run Up To Current Time is turned off.