WS2812Serial 400 or 800 kHz

[autouser]

Does anyone know if the ws2812Serial library use serial to drive neopixels at 400khz or 800khz.

 

[PaulStoffregen]

It is 800 kbps.

 

[ascott00]

Any pointers on how to modify the library to run at 400kHz? I am trying to drive a run of 60 APA106 LEDs with a Teensy 4.0 (via a 74AHCT125) and the last 15 are flickering significantly. I can duplicate the flickering effect using the Neopixel library with the 800kHz option - it is fixed when the 400kHz parameter is selected instead.