If you're interested in AU and memloss, perhaps saveourearth would be a good place for you? It has both themes, as characters get reincarnated on modern day Earth, specifically the UK (there's a page with info about life in Britain to help with building an AU). Due to their different upbringing in their new life, they are encouraged to differ from the original in three to four ways, but a major game mechanic is that characters will then regain parts of their former lives, be in memories, abilities, items, personality traits or something else.

The game is backtag friendly, on dw and neither sex nor horror themed (the latest plot mingle has a bit of a horror theme but it's also the Halloween mingle so that's an exception). In my definition, the pace is slow, but I know that pace is very ymmv so that'd be something that you could better look for yourself. There is only one IC comm, saveourearth, so you can easily see how often (player) posts and (mod) mingles go up.