Now it works fine

I'll try that, but it is probably not the only reason
It may be due to the high number of visits, maybe some search engine indexing the site (or a dumbass trying to download all the contents)

If you think Top Gear could be one of the reasons then please remove it from the list, it's quite annoying to be on the site and get this message every time you click on a new link

One thing that may also slow down the whole site is having things like Top Gear in the last completed: due to the amount of cars on this page, if lots of visitor check it...

This is due to the site becoming bigger, so slower, and with more people on it
Database size has always been a problem and will always be, hence all my comments about useless background cars, useless quotes, useless thumbnails, etc.
One thing that I'll do to optimize the speed is to have the makes stored in a separate list instead of just a text field. I am not sure that it will help a lot, but it can't be bad anyway.
I'll do something similar for usernames in comments (only problem will be the lost of unregistered usernames in very old comments, which is not very important)

Yes, me too

+1

I have the same problem...

Lately, very often

found the problem and fixed it... It is not what I thought at first.
I absolutely have no idea why this happened. It should have worked for everyone or for no-one, there is no logical reason why that was partially working

edit: one possibility: it failed only for those who did not visit the site just before the upgrade AND who had the auto-login option (hence why subzero had it fixed by cleaning cookies...)
But still I wonder why it was working on my local server and not on OVH's server.