adafruit wrote:you -always- need decoupling caps, speed has absolutely nothing to do with power supply caps
Might be handy to include a note on this page then:http://www.ladyada.net/learn/avr/programming.html
I only found this surprising because I had programmed chips without decoupling caps in the past. I guess I was lucky. Very well, religiously assimilated into my mind: "ALWAYS DECOUPLE"
When I had decoupling explained to me, I was told you need the caps to smooth out the noise created by rapidly switching ICs, however when I think about it, the default speed of an AVR is 1MHz, which is still pretty blazing fast.