Site is very slow, 404 nginx errors

For about at least the last 30 hours, the site is all of a sudden very slow for me. Page load times of over 10 seconds are not uncommon, and sometimes it just gives me a nginx “404 not found” error. It worked fine up to 2 days ago.
 
Once in a while it loads quick, but I can just refresh the page a couple of times and I’ll hit a slow one or 404 in no time. I have this problem both on my Linux/Firefox 21 which I usually use, but also when I tested it in a brand-new installed Windows XP VM with both a stock Firefox 21 as well as Opera 12.15  
Thumbnails usually take ages to load, the big picture on the page itself often too.
 
It’s not limited to just pictures, it’s the entire booru doing this, including the forums, userprofiles, and even the donate page.  
Other sites load fine all the time, and 404’s are like a really bad thing in the first place, so what is going on? I waited with creating this topic to see whether it was perhaps some server thing yesterday, but it’s still doing it so there.
 
EDIT: I should probably add that it makes the site pretty close to unusable.  
EDIT2: I got another 404 when clicking the Post reply button to edit my comment the first time…  
EDIT3: clicking View Versions does show that it came through though.

I’m encountering the same problem, pretty much.

Same.
 
Boy, feels just like 4 months ago.

Me too, which is surprising.
 
Somebody should turn the servers off and on again.

It’s also been pretty slow here. It started yesterday afternoon and is still slow today. I’m also getting 404s every few images. Especially with updating tags.

It looks like the images tagged with spoiler:equestria girls are failing to load.

@Dr Outback  
that explain why i couldn’t access to that pic to tag it “equestria girls” (but other people can access to them)

@Dr Outback  
Oh, so it’s a problem. I thought I was the only one. I want to keep these images spoilered until after I see it but I can’t even load the option to see them…

The site should be returning to normal now; we’re trying out a new set of application servers as part of this restoration, but Trixie was out of service for over a day. Apologies, but should be better now. We’ll be continuing to tweak things over the next day or two.

The site is working for me but for some reason when I try to look at the images tagged spoiler:equestria girls it keeps giving me an error message.  
Update Edit: I managed to get around it by turning off the spoiler setting for that tag.

@Clover the Clever  
The images tagged with spoiler:equestria girls still aren’t loading for me.  
EDIT: I did what apegacine mentioned, and the problem seems to be solved.

Well of course turning off the spoiler setting works, but I’d rather not have to do that…

We’re aware of that and it’s on our to-fix list.

Everything seems fine again here. I can’t comment on the equestria girls spoiler thing because I’ve hidden that tag anyway.

We’ve fixed it anyhow now.

@Clover the Clever  
Thank you very much!

Hmm, while I’m not getting the errors, the site is still lagging for me. Any suggestions?

The site isn’t lagging for me. But certain images won’t show. The page would load as usual, the image just won’t show no matter how many times I refresh. Is this a server sided problem or mine?

Server-side. You may want to disable server-side scaling in your user preferences. We’re making changes to improve the site performance, as ever.

well the 404s seem to be gone, but now all the images (aside from thumbnails) are broken.

This should now be fixed. We’re tweaking the behaviour of image display on image pages to accommodate slightly more efficient (server-side) ways of rescaling content in future.