When running servo controls that involve console commands, each console command takes about 500ms extra, potentially 5 seconds or so for complex controls. This seems to be due to the console freezing.

Commenting this line brings the controls back up to near-instant response.
https://cs.corp.google.com/chromeos_public/src/third_party/hdctools/servo/drv/pty_driver.py?rcl=9291fb6606ba0845ea9f08069258ade935170789&l=50