I’ve got a Windows Vista laptop that’s about five years old. It’s a dual CPU machine with 2G of RAM. After installing several bits of new software, I noticed that it was unbearably slow when logging in, switching users, and logging out. The CPU use wasn’t too high, but the disk drive light indicated that it was being kept very busy. I booted Fedora 14 Live from a USB drive, and the computer was snappy and responsive.
I monitored the system processes, and most of the I/O reads and writes were attributed to svchost. On a Linux or UNIX machine, it would have been easy to identify which service was the culprit because each service (known as a daemon) runs as a separate process. But in Windows, services run as part of svchost, making them hard to identify and monitor individually.
Since I didn’t know what was causing the slowness, I guessed and uninstalled Mozy backup. Nope. That wasn’t it. My computer was still slow. So I uninstalled Norton 360. Problem solved. The computer is responsive and snappy again, and has remained so for the past month.
Shortly after I uninstalled Norton 360, a neighbour called and asked if I could figure out why “the Internet was running so slowly”. He thought he had Windows 7. When I arrived, I found that it was Windows XP running in 512M of RAM. I booted Fedora 14 from my USB flash drive, and found that his computer ran quickly and loaded web pages quickly. His Windows XP machine was running Norton 360, and task manager showed that Norton processes were consuming large amounts of disk I/O.
I uninstalled Norton 360, and on the recommendation of a smart colleague, installed the free Microsoft Security Essentials. The computer ran quickly after that. My neighbour is pleased. I went home and installed Security Essentials on my Vista machine, with little noticeable slowdown.
My conclusion is that Norton 360 may only be appropriate for newer hardware and generous amounts of RAM (4G or more).