"light_ws2812" library 10x slower than required (AVR C, ATMega328p int. 8Mhz)
In Atmel Studio, doing a
#define F_CPU 8000000UL
at the beginning of main.c was not sufficient. I've gotten rid of that code, and created a Defined Symbol
F_CPU=8000000UL
under

Toolchain&gt;AVR/GNU C Compiler&gt;Symbols.

I'm still not really sure why defining F_CPU before even calling the libraries was erroneous; even util/delay threw some warnings sometimes (if I had F_CPU as an Undefined symbol, I think).