The main reason I want to use Houdini GL is that I have a hard time getting HUSK with Karma to render fast enough for quick previews of our stages. A simple 100 frames 640x480 render of a rotating rubbertoy, takes over 3mins on my workstation, even in the worst rendersettings, I could come up with. USD's usdrecord takes 4 secs for the same sequence.
usdrender lop is doing the writing out, and then reading+rendering via husk; usdrecord is just reading the usd
If you turn on the "Render All Frames with a Single Process", the usdrender node will write the usd to a single file, then in one process render out frames (this is more along the lines of what usdrecord is doing)
I just tried your hip file, and when rendering all frames in a single process, my 8-core machine takes ~6s to render images to disk, and ~20s to render the 100 frames to Mplay.