Maybe you mistaked downloaded the beta NIS 2007 that are already expired, I got it from here
and click on Try Now. I checked my task manager for processes and memory usage for NIS 2007 compared to previous NIS 2006.
NIS 2007 at idle have 26 processes and 156Mb memory usage compared to 40-45 processes and 290Mb memory usage with NIS 2006, at load with full scan NIS 2007 have 27 processes and 190-240Mb memory usage compared to 41-46 processes and 370-410Mb memory usage with NIS 2006.
I am very impressive at NIS 2007 used lots less processes and memory, loaded into memory instant, instant phishing protection which are very much faster than Internet Explorer 7 phishing protection took 5 to 7 seconds to scan a website on my laptop. I noticed Ad-ware and pop-up blockers as well as anti-spam filter are absented in NIS 2007 while previous NIS 2005 and 2006 had the features build in it, I think it the reason Symantec listened to beta testers and customers feedback complainted about the bloatware and reources hogs, they decided to removed 3 pointless features and write from scratched. Symantec finally did the right thing to removed 3 useless features because both Internet Explorer 6 and 7 already has the best pop-up blockers and also you can create spam filter in Outlook Express 6
that do better job than any AV programs bundled anti-spam filters. It a shame they removed Ad-ware blockers, they are very good but there are alternative free ad-ware you can find on Internet.
Intel Core i7 3770K, Corsair H80 liquid cooler with Noctua S12-1200 fan, ASUS P8Z77V with UEFI 2003, 16GB Samsung Green 30nm DDR3-RAM, Pioneer DVR-217DBK 22x DVD-RW, Corsair AX850 PSU, Western Digital 2TB SATA3 hard drive, CanonScan LiDE 210 scanner, Microsoft Internet Keyboard, ASDA Wheel Mouse Optical, 32inch Sharp LC32LE600 LED TV, EVGA Geforce GTX 670 SC 4GB with Geforce 326.80 driver, 30Mb broadband Virgin Media VMDG480 Super Hub, Aspire Xplorer Midi Tower, Windows 8.1 Pro 64bit.