Performance of NIOS II is 15.5 DMIPS...

If you want higher performance, I suggest you try using the Nios II/f instead of the Nios II/s core.

It runs at a higher frequency than the Nios II/s so you might be able to make timing.

It also takes fewer cycles to execute instructions so offers higher performance.

In our current Nios II 1.1 release, the data cache is manditory in the Nios II/f although you can make it as

small as 512 bytes to minimize resource usage. In our upcoming Nios II 5.0 release, the

data cache will be optional (you can specify a size of 0 bytes).