Let's just say I don't think any coder can help. Who can help are server & network admins. The guys who run the machines... Anyway, they're on it now, let's see how it goes. No matter what state the site's gonna be in in a week's time, I'll then write another mail to Gary, just to see what they told him was or might be the reason.
Edit: Whoopsie, just got another Mail asking for how it looks. And it's looking pretty good for me, site loads fast again on all three my client machines, from XP x64 over Windows 11 all the way to FreeBSD UNIX. I'll ask him whether hew knows what the reason was!