I've been scanning my network for new hosts using this command:
nmap -v -sn 192.168.0.0/16 10.0.0.0/8
I have a lot of users in my network. Does the nmap scan slow down my network traffic or do I just have a load due to users?
Since nmap will be performing a ping scan in chunks of 4096 host addresses at, at least, 2 ports per host address, (corrected thanks to @Trickycm), it will be generating quite a lot of traffic so yes it will be impacting your other network traffic to some degree but depending on the number of pings and the rate pinged at I would expect the impact to be moderate.
You can add options to reduce the impact:
--max-retries <tries>: Caps number of port scan probe retransmissions. --host-timeout <time>: Give up on target after this long --scan-delay/--max-scan-delay <time>: Adjust delay between probes --min-rate <number>: Send packets no slower than <number> per second --max-rate <number>: Send packets no faster than <number> per second