Using what clock?
I thought that 1 Mhz internal was an option - I was wrong . But assume a 1 Mhz crystal.
1 MHz = less power.
1 MHz = 8 times slower.
I realise that, but imagine two Atmega328: system #1 - 8Mhz divided down to 1 Mhz. System #2 - 1 Mhz crystal, no divisor.
Both systems have a 'final' clock of 1 Mhz. I assume that both would complete a loop of (say) 100 iterations in the same time.
Are there any any notable performance/efficiency differences between system #1 and system #2?
Also, if I programmed an Arduinos fuses to use the internal oscillator, do I need to remove the crystal to ensure stability?