Nios interrupt response time

Take a look at the vic an example designs (http://www.altera.com/literature/an/an595_vic_collateral.zip) to get a reference point for Nios II interrupt performance.

I'm not sure what (exactly) could be causing the large delays that you're all seeing, but these are largely system dependent. I recommend starting with small, simple systems (like what's included in the examples) and building (interface-by-interface) from there.

@mikebray: What speed is your UART? The Altera supplied UART has no internal buffering, so I'd expect dropped data if the CPU's not able to keep up.

@All: External memory can cause large and unavoidable latencies. Be aware of this and design your hardware and/or hardware interfaces appropriately.

Cheers,

- slacker