Counting Pulses with Digital Input

What would be about the fastest an UNO could count pulses on a digital input in HZ?

Thanks,
JP.

With some hardware + internal timer you can do quite impressive things like:

8 Mhz is about half the clock speed. Fast enough?

What are you planning to build?

8 Meg, holly cow! I only need 10 kHz.

Thanks,
JP.

P.S.: Thanks for the link too.

JP.

10 Khz you can do with attachINterrupt() and use millis() or micros() to calculate the frequency ...