Hi Rod,
Well as for the categories, it seems that it's when I go back to homepage from them that it's getting slow, so I m not even sure the categories have a problem at all, whenever I try to open categories and access products it's working fine though not as fast as before.

As for the slowness to the homepage, it's random really.

For the Admin, it's been super slow ever since the problem started 2 days ago... pages take time to load and even when they display you still have that small waiting for.... at the bottom left corner of the page which means the page hasn t finished to load completely.

My latest back up of files for zen cart is recent, from the 22nd of February and I haven t done any other mods after that so it should work well, I replaced the admin and the includes with new files but I still have the same problem actually...
I didn't do any other changes, I just attempted to add that facebook like box and removed it and edited back everything I had changed.

Now the funny thing, you say it could be my own computer or even internet connection causing this: I was somewhere else when I did the mods, and I came back to my shop to leave my computer, and later in that same shop I tried to work on my web store and realised it was not working well, the first thing that came to my mind when I saw the admin was so slow was "internet connection" and even maybe my computer but I haven t tried to open the admin on any other computer or tried in a different location with a different connection. I will try that and it will help to pinpoint where the problem is...hopefully. Cos I had a super fast working web store and admin and now it s annoying to even edit one product....
Thanks