We're running into some performance issues where levels will start hanging while processing HDAs. Is there a log that where we can view the state of the processing and potentially see where the trouble is coming from?

There's the plugin logging categories you can turn on with ue4 console commands:

And then there's the Houdini logging environment variables HOUDINI_ERRORLOG_FILENAME and HOUDINI_ERRORLOG_LEVEL.

Excellent! Thank you.