ID 270487 - Animated Alembic geometry slow to load on frame change when used as proxy

Problem summary

When heavy, animated alembic geometry is loaded as a proxy in the Viewer, changing frames is much slower than when the same geometry is loaded normally in non-proxy mode.
Once all the frames have been stepped through, the frame change is quicker, but the initial caching of each frame seems to be much slower than when the same alembic geometry is loaded in non-proxy mode.

Customer reported version
Katana 2.5v5

Steps to reproduce

1. Download the attached assets, then open the attached scene, which contains an Alembic_In node loading an alembic cache with some animation on it, and change the file paths in the scene to point to the assets.

2. View the scene from the AttributeSet node and expand the scene graph all the way to /root/world/geo/asset/proxy/proxyShape

3. Change the frame a few times on the timeline and note how quickly the Viewer updates.

4. Collapse the scene graph so that the it’s only expanded to /root/world/geo/asset

5. Change the frame on the timeline again. Result: The Viewer updates much slower.

Workaround
Unknown.

Reproduced by support
Katana 2.5v1, 2.5v5 Windows 7
Katana 2.0v1, 2.0v5, 2.1v1, 2.1v5, 2.5v1, 2.5v5 RHEL 6.4

Expected behaviour
It may be expected that the Viewer update speed should be the same for proxies and geometry locations.

Actual behaviour
The change between frames is much slower on the proxy.