The interruption caused by having McAfee Antivirus is even worse.
This only measures boot time. McAfee, on average, saps 20 to 30 percent of your CPU when it's in normal (read: Scan Everything) mode. It also kills your I/O.
Norton, on the other hand, is much less nasty.
Considering that the only people I know with 1,000 fonts, personally, work in either the graphics or design industry, I don't see that as much of a slowdown
.
Of the two AV programs, I'll pick Norton as being the least nasty. This set of stats only shows startup. Give me 30 minutes of normal usage, and the results will be completely different.