I don't hate Bugzilla because it's slow or because it's complicated. For others I sympathize and wish those things were better.
I hate Bugzilla because looking at it offends that little scrap of designer that's still alive somewhere in the back of my brain.
Here's the section of Bugzilla's search page that I use the most
There's much wrong with this section, from the unnecessary text to the expando triangle that isn't actually clickable. But those aren't nearly the pain in my eyes that is the completely broken alignment of just about every element in that section. I challenge you to find a single item in that section that's properly aligned with any other. The text fields aren't even the same length!
Here's a quick mock I did of the same section with the same search capabilities:
It's not gorgeous, but at least the elements line up.
I don't know much about how the Bugzilla pages are put together, but I think it's just a big mess of HTML forms so it seems like it couldn't be that difficult to pretty it up some. If you're a web developer and you'd like to make me and lots of other people very happy, perhaps you could do a little clean-up to at least get some basic alignment improvements. Help‽