Achievements overheads

A few patches back Blizzard removed some of the statistics tracking from their new achievements system: the way it worked is that (e.g.) every time you do damage or take damage it looks to update the max damage statistic. That's a tiny overhead on every attack you ever do, and the tiny bit of cpu distraction really begins to add up, especially in a 25-man raid where you can afford it the least.

Why not just log everything, and then process it during downtime, such as resting in an inn? The character could even be notified in their system/chat log of updates, or possibly even some kind of emote visible to others.

You could even stage out the processing a little bit, so instead of it being a spam attack of statistics it trickles in over about five minutes or so .. just enough to have it prompt social discourse and the occasional /flex.