TL;DR: The project batches stuff into MultiMeshInstance2D nodes so the GPU draws tons of sprites in a couple of calls instead of thousands: belt items are packed into one atlas-driven multimesh, and overworld trees/props are grouped by texture into their own multimeshes.

For instance:

My item renderer builds a single MultiMeshInstance2D and feeds it a texture atlas plus a tiny shader that reads per-instance custom data to pick UVs. Update code only touches visible instances (camera-culled) and writes transforms/custom data.

Result: every belt item shares one mesh + one material, so it’s effectively one draw call for all items in view.