--Tracked down slowness of pan/tilt execution to tcdrain() used to send integer speeds to motors. tcdrain() is necessary to ensure that integers get sent to motor controllers--removing it results in missed motor commands.  Reduced tcdrain wait time to minimum allowable (100ms), and also implemented code to skip sending motor command when motor command is a repeat.  That seemed to resolve the problem.
--Finished implementation of command parsing and sending to motors within emperor.cpp.  Also removed debugging printfs.