Bug overview description.
When looking up images that may be subject to blacklist, blacklisted images still show up in a split second before disappearing when the page completes. This is most apparent when searching for tags you've blacklisted but may not be noticeable depending on the browser you use and your internet speed.

What part(s) of the site page(s) are affected?
Browsing images.

What is the expected behavior?
Images subject to blacklist should not load at all.

What actual behavior is given instead?
Blacklisted images are loaded and displayed very briefly until page finishes loading.

Can you reproduce the bug every time?
Yes (I use Google Chrome with a 20Mbit internet connection).

What steps did you take to replicate this bug?
Searching for blacklisted tags (easiest method).

That's not really as much a bug as it is a limitation of the current blacklist implementation.

The basic gist of the blacklist's workings is that it stores a small cookie on your computer with the tags in it, the server presents you a filled page of search results, and once the search results have loaded a small snippet of JavaScript compares the blacklisted tags with the tags of all images in your search results, then hides the matches. Depending on your CPU power this will take anywhere from a few milliseconds up to a couple seconds on very slow devices.

To fix this we'd either have to implement server-side blacklisting (would be nice but very computation expensive and not feasible at the moment), or have everything hidden by default and have JavaScript show anything that doesn't match the blacklist (which would effectively break the page for anyone without a JavaScript capable device/browser).
While we would love to have the former sometime down the road it won't be anytime soon.

NotMeNotYou said:
have everything hidden by default and have JavaScript show anything that doesn't match the blacklist (which would effectively break the page for anyone without a JavaScript capable device/browser).

Would it possible to program the blacklist so that it checks if the user has a JavaScript capable device/browser, then checking the user's blacklist before loading? If the check fails, due to running on a non-JavaScript capable device/browser or having an empty blacklist, then the page loads normally without hiding anything. It'd solve the problem you mentioned, right?

as all matter goes towards entropy, all websites go towards an unmaintainable pile of spaghetti code and bad markup.

optimising this client-side would take a lot of effort for a small benefit.

You can minimize the effect by changing amount of images in single page from user settings either so low that the code runs faster or so high that blacklisted images are somewhere below where you have to scroll.

Mario69 said:
You can minimize the effect by changing amount of images in single page from user settings either so low that the code runs faster or so high that blacklisted images are somewhere below where you have to scroll.

And if you just have a slow computer, when you load up a new page switch to another tab and only go back once the loading is done.