Preferences > Performance Options
Controls updates of animation expressions, constraints, construction history and locators.
Update Options
These controls determine when updates occur to various items: construction history, locators, trim surface boundaries, expressions, constraints, IK handles, clusters, and action windows.
Each of these item updates shares the following toggles (construction history updates share only the second one):
After Modification
When After Modification is OFF, the display of expression, constraint, IK, cluster, and locator updates is suppressed. When set to ON (the default), updates are displayed as they happen.
Updates are stored, so if After Modification is set to OFF for a long time and then turned ON, all the stored updates are done immediately.
During Transform
When During Transform is ON, updates of the expression, constraint, IK, cluster, construction history and locators occur as you drag the mouse in any Transform operation (such as Transform > Scale 
). When During Transform is OFF, updates occur when you release the mouse after an Transform operation. By default, it is ON for constraint, IK, cluster and locator and OFF for expressions and construction history.
During Playback
When During Playback is ON (the default), updates of locators, expressions, constraints, IKs, and clusters occur for each frame during playback. When it is OFF, the updates occur at the end of the playback operation.
Note that:
- Even though construction history can update for each frame of a playback, it may not do so for a rendering of a playback because SDL does not support all construction history operations.
- Constraint animation can be updated during playback. However, to render constraint animation, pick the skeletons with animating constraints and select Animation > IK > Run IK
to capture the constraint animation of the skeleton with keyframe animation.
Trim Surface Boundary Updates
When trimmed surfaces are animated so that their shape changes, the system slows down. You can speed it up by disabling the display of trimmed boundaries.
When trimmed boundaries are disabled, trimmed surfaces only display their interior curves, not their boundary curves. The display of trim boundaries can be disabled in two ways:
During Playback
If toggled OFF, the trim boundaries will not be displayed during playback and playback will operate faster.
The benefit of these two options is only apparent when the trimmed surfaces are being deformed. Animation at the transformation level does not benefit from this optimization.
IK Updates
Sync Geom After Write SDL
The IK Updates section has this option. If there is Single Chain IK in your model, Write SDL steps through your skeleton animation internally, and then does a viewframe at the end to restore the skeleton’s state to the current frame.
If the Sync Geom After Write SDL option is OFF, it will assume that your geometry was up to date for the current frame, and will not recompute the deformations (recomputing the deformations could take several minutes for heavily clustered models).
If you’re doing a lot of tweaking on the model, and you don’t usually do a viewframe/playback immediately before Write SDL, you may wish to turn the Sync Geom After Write SDL option ON, so that the geometry and skeletons will be in sync after WriteSDL completes.
Playback Other History
The IK Updates section has this option. It lets you specify that ALL construction history (not just blend surfaces) are updated during playback. Normally only blend surfaces can be animated within the renderer, and other construction history is held static.
Action Window Updates
After Modification
Lets you choose whether or not transforming keyframes or curves within the Action Window should update the modeling windows. If toggled ON, the During Transform options are displayed. You can choose between updates just after the transform (After Modification), or during the transformation (During Transform).