That's interesting, I thought that the whole LoD series of a used sprite entity was loaded into the video memory when first using the entity. This does not seem to be the case then. Or if you mean by custom LoD that you have to morph from low to high res entity entirely, then I think you would have to find a way to preload the higher res ent into video memory. The engine could not do that unless told exactly which ents (sprites in this case) to preload. So, you would have to script that part in which your sprites-to-be-used are preloaded and the removed from the level. The entities are thereby initialized and preloaded into the video memory and there should not be any time delay when you eventually create and use your entity in the level.

I know, this seems cumbersome, but it seems to be the only way IMO to avoid the time delay when morphing or creating ebtities that were not in the level to begin with.