I used to have a good proportion of my O/Os thread under spoilers, but it didn't actually seem to make the thread load faster.
What has made it load faster for me is first the new site, which is at least twice as fast as the old, but more dramatically: using https at least on picture laden threads that I view often.
https loads noticeably slower (than http) the first time around on a thread, but subsequent loads, even days later, are lightning fast. I think it has something to do with the way Veks has it cached. (either that or https bypasses some bottleneck on the way from the site to me).
[I went from 10 second loads of my O/Os on the previous host to 4 seconds on the new one, and then to less than 0.2 seconds using https here.]
You might want to try it and see, if you aren't already.