Disclosed herein is a supplemental cache for use with a graphics processing unit. The supplemental cache can be used to supplement a vertex cache used with a graphics processing unit. The supplemental cache stores vertex values generated in assembling primitives from vertices provided to the graphics processing unit as part of an image geometry. Generated vertex values associated with a vertex determined to be shared by two or more primitives can be retrieved from the supplemental cache, so as to reduce the need to perform duplicative operations to generate vertex values for shared vertices.