You are right about the 1us. I'm using this to be able to fade between colors.

If I turn on the red led, wait 333uS, then turn on the green led, wait 333uS, and then the blue led and wait 333uS and then loop again, i have a white color at about 1000Hz, with no flickering. If i then increment the pauseus 333 for red and decrement the pauseus 333 for blu the color shifts smooth from white to about orange.

I use the pauseus command at 8Mhz, which has a shortest delay of 12us. In the fade cycle this results in that one (or two) led are almost off, but not completely. The last 12 cycles the led stay on for 12us, and in the last cycle it will turn off.

It works perfect except for the last few cycles ....