Also, forgot to send this to the list earlier:
just to say that I've seen the same:
I tried para-virtualised and it didn't help and also ran into a nasty
I've gone as far as disabling CGD now because a) I wondered if the
overhead of encryption wasn't helping b) I can just hit reboot now
when the clock drifts and not have to worry about typing in my
password (I'd long grown fed up of the inconvenience of encrypted
disks in the cloud)
The next thing I was going to try was a fresh install because I also
switched from Xen to KVM "in place".
I've also noticed a similar issue to you:
On a fresh boot, mutt will switch between my mailboxes quickly. After
a few hours/days of running it'll start taking longer and longer; This
is mutt straight into a local maildir since my Linode NetBSD is also
my mail host. So weird.