How do I increase performance during a scene load?

I'm streaming a large number of world tiles from a hard drive (SSD) using scenes stored in asset bundles. Each tile is just a piece of terrain and a single texture. Every time a new tile loads, there is an intolerable performance hit that occurs during "Application.Integrate Assets in Background". A deep profile reveals that the primary culprit is a recursive qsort on an Array that is called by InternalStaticBatchingUtility.Combine().

Does anyone have suggestions for how to avoid this?