QBiN wrote:

To answer the questions of why SP3 and what services/processes I'm talking about, let me take a step back. This PC was a "daily driver" in the early 2000's. So it got all the latest updates etc.. including SP3 and new versions of IE back in the day. It was never rebuilt as a lean retro machine. It's just a survivor.

Just to check if my understanding is correct, you've never rebuilt this machine for the past 13 years or so?
If that is the case, then I'm not surprised of this machine's slow performance. The registry probably contains a number of unused entries of programs you've long since removed and you might still have processes running for apps that weren't properly uninstalled (you might even have some adware/malware lurking around in there as well).
I suggest you perform a fresh installation. You should then see a considerable improvement in performance.

jesolo wrote:

The registry probably contains a number of unused entries of programs you've long since removed and you might still have processes running for apps that weren't properly uninstalled (you might even have some adware/malware lurking around in there as well).

There is no shortage of sites that will tell you that stray registry entries have no (or at least an extremely minimal) effect on system performance. And everyone else is, of course, selling something.

I might also suggest that the risk of adware/malware would be minimized by Microsoft's frequent pushing of the Windows Malicious Software Removal Tool.

jesolo wrote:

I suggest you perform a fresh installation. You should then see a considerable improvement in performance.

+1

Even for good 'ol XP, 13 years is wwwaaaayyyy too long a time between re-installs...