I run Malwarebytes and after I upgraded from Apprentice to Indie when ever I would add a node or move around in view port, sometimes it would take 5 or more seconds to react. I uninstalled Malwarebytes and Houdini is flying, no hesitation. it did seem to work fine before I upgraded to I wonder if that had something to do with it. I might try reinstalling Malwarebytes and see how it plays with Houdini.

edit: I sent email to support and they believe Malwarebytes is hitting the executables, which would make sense.