hmm, you are scanning your local network, so intenet speed is not a factor change the scan speed.
how big is your network? ie: how many devices appear in your user list? 5-10 minutes is not normal, unless you are in a large network like in airport or office
If you turn on fast scan it should stay fast scan unless you change it, there was a bug before 1.7.0 that can’t save fast scan. now it should been fixed.
also, how big is your network? if it is a B class, normal scan should take longer than 10 minutes. fast scan should finish around 2 mintues.
c class should finish in 10 seconds in normal scan, 2 seconds in fast scan.