Faster method for per vertex color?

[SonyBoy]

Got my second project where I've used MASH to generate random colors on instances. I'm following the same workflow from a previous project where I then exported the MASH reproMesh as an ABC for rendering, bringing it back in and generating random color assignment with the randomByPolyShell attr. on a sampler info node.

This time around I'm noticing that this seems to really slow renders to a crawl. Rendering the MASH network while still live gave me random colors fairly fast. By comparison, using the sampler info randomByPolyShell attr. to drive color distribution via a ramp is exponentially slower.

Is there any other way to pipe PV color from an alembic file for rendering in this way that might be faster?

[hermit.crab]

I am not aware of another method. Otherwise, I don't see much of a rendering time difference between a live MASH network and the exported Repro. Maybe you could share the scene?