Hi @romaingrosse,
Thanks for clarifying the specs and SDK you are using, along with the code sample and the fact that you have a short update delay to not miss any of the events from the eye tracking engine.
I believe the EyeX Controller can deliver eye tracking data up to 60 Hz, and that is once per 0.017 seconds, so it could actually still be a problem of missing some of the events from the eye tracker if your update delay is set at 0.02 seconds. Would it be possible for you to test with an ever shorter update delay?
There might also be a bug in the Slow version of the data stream – the symptoms seemed similar to an old known bug when I talked to the guy who has implemented the data stream algorithm in the eye tracking engine. Have you seen the issue also with the Sensitive filtering?