There seems to be some condition of the Hub where, when in debug mode, it starts consuming a lot of CPU and slows down. I'm seeing this with the serial connection where I've left it alone for maybe 10 minutes. If I then turn debugging on, it goes into this high CPU, slow in sending data to the client mode. The Arduino is sending data from the serial port every 10 ms. It's as if the data is queuing up because it can't write it to disk or something. Everything goes back to normal once debug is turned off.