Aha, tried this with a /28 (with 2 addresses that are up) and it takes about 4 minutes.

Will do some further investigating but you're suggestion seems to have done some good. The weird thing is that my last port isn't found as a service:

32770 : sometimes-rpc3 
32775 : sometimes-rpc13 
32776 :
[download]

Thanks for the input!