Some comments about UI text inline:

Again there are plenty of 'unused parameter' warnings. Please set up your compiler to emit those, or use the Linux Custom Branch buildbot to build the branch with GCC (which will emit those warnings).

• USD Import: merge prim with parent xform.
• USD Import: remove mesh modifier duplicate code.

Yes, my original branch usd-importer-T81257 has logic for merging an Xform and prim into a single object. I will port this code to the usd-importer-T81257-merge branch as well. Thanks for pointing this out.

Exporting a single Mesh object to USD and then importing it again produces two objects: an Empty and a Mesh object. I don't think this is a good approach, as every time a scene is exported to USD and imported into Blender again the number of objects will double. It's also not what is described in T81257: Initial version of USD Importer, which references the Alembic importer. That importer has logic to determine whether separate XForm + Mesh nodes should be joined into a single Mesh object, or whether to split them up into an Empty and a Mesh object.

• USD IO: fixed warnings.
• USD Import: missing include.
• USD Import: warning fixes.
• USD Import: format fix.
• USD Import: warning fixes.

The patch doesn't build for me, and has lots of warnings too:

Updating D10700: USD Importer

I've done a quick pass over the diff, to see if it can be accepted as-is (or with minor changes) and thus be in time for Blender 2.93 bcon2 or not. I feel that there are too many changes needed, though, and that thus we'll have to aim for inclusion in Blender 3.0.

Thanks for pointing this out, Sybren, and I apologize for the oversight. I've removed the video.

@Michael Kowalski (makowalski) Please don't include icons from proprietary software in any comment. These are covered by copyright and other nastyness; see Ton's recent post on devtalk for more context.

As an update, I recently extended the USD importer experimental instancing option to support collection instances, to allow editing of instance prototypes after import. (The change is committed to the usd-importer-T81257 branch.)

Tested a build based on the usd-importer-T81257 branch. The basic Pixar kitchen loads fairly quickly, and instancing saves memory as expected.