Hi @matematiko, I don’t think that 2.100 pixel in a row will work.
The maximum of 1.500 pixel is defined in WLED00.ino line 408++:
#define MAX_LEDS 1500
#define MAX_LEDS_DMA 500
I think you could get problems with the ESP rebooting or getting unstable, as the processing would take reasonable longer.
But: give it a try 