On Thursday morning at 4:00 AM PDT, there will be rolling restarts across the US realms to apply a "small server-side fix" for an unspecified problem. (If anyone notices any specific performance differences after the realms come back up, I'd be curious to hear it, however!) If all goes as planned, each realm should only be offline for 15 minutes. While this shouldn't have much impact on players in the US, it seems to hit prime Australian playing time. Fortunately the scheduled downtime should be brief, and you can get back to your normal playing quickly.