NMAP seems to have stopped, or my scan is taking a very long while. Why is this?

The timing options can make it take a very long time. I believe the -T Paranoid ( -T 0 )option waits up to 5 minutes between packets... now, for 65000 ports, thats 65000 x 5 = 325000 minutes = 225 days!!

-T Sneaky ( -T 1 ) waits up to 15 seconds between scans, and is therefore more useful; but scans will still take a long while! You can use -v to get more verbose output, which will alert you as to the progress of the scan. Using -v twice makes the output even more verbose.