This one has been around for a while (possibly longer than 6.7, I just think that was when I first noticed it) so it may have been reported already.
I leave the dashboard open a lot of the time just for general monitoring.
When navigating to another page after it's been left idle for some time, there will be a large spike in CPU usage (on the client machine), and a big drop in memory usage.
I haven't charted this, but the affect is noticeable after about a an hour; on moving to any other page, there will be a delay of maybe a second or so. After a couple of hours, it's several seconds, and several hundred megs of RAM reclaimed.
I'm not sure exactly when it happens - maybe over night - but Chrome will eventually "Aw, Snap!" and crash.
Certainly not the highest of priorities I know, but I figured I'd mention this as given one of the things we'll be getting in 6.10. I wouldn't want this to detract from an otherwise sanky new look. 😎