Preview Setting

Start Percent: Controls the percentage of primitive positions that are calculated and discarded before generating primitives for preview. Use this if primitives are being created in a specific order (not randomly).
Percent: Controls the percentage of generated primitives you want to appear in the preview. Turning this down speeds the refresh while providing a good representation of the final render. Ranges from 100 to Start Percent.
Limit: Sets the maximum number of primitive generated in the preview.

Use this option to reduce the number of primitives generated on large polygon objects to avoid Maya performance issues.
Only primitives in the view: Previews primitives in the camera view (frustum). This does not affect the final render.
View Margin: Controls how far (in degrees) a primitive can be outside the view and still be included in the preview. Use this with Only primitives in the view.
Draw

Patch Names: Displays patch names in the view.
NoteSelect the geometry or description before activating Patch Names or they do not display.
Face IDs: Displays Face IDs in the view You can use this to determine if the XGen face IDs of the mesh are different from the Maya face IDs. This can be the case when a non-quad only mesh is being used. XGen will subdivide the non-quad face into quads and assign face IDs to those sub-faces.
NoteSelect the geometry or description before activating Face IDs or they do not display.
Primitive IDs: Displays an ID number for each primitive in the preview. Primitives are numbered per-face.
Vertices: Displays the vertices on the primitives.

The vertices displayed are not always those of the computed primitive. Turn on Poly for a more accurate display of vertices.
Poly: Displays the primitives as simple polygons, not smoothed.
Culled: Displays culled primitives in the preview.

Unit Cube: Displays a unit cube around the contents of the archive files. This applies to Archive primitives only.

Primitive IDs At: Controls the location along the primitive where IDs display. 0 is the base of the primitive, and 1 is the tip.

This is only enabled when Primitive IDs is turned on.
Primitive Color: Sets the color used to display the primitive. When set to 0.0, the primitive displays with its default shader color.
Guide Color: Sets the color used to display guides.
Spline Segments: Smooths previewed splines by increasing the number of linear segments drawn for each CV in the spline. Higher values can slow the preview generation. You can use Spline Segment as sampling value for splines when generating a preview.