Lxc list -- now running very slow

My little cluster of 4 machines with about 100 containers is giving a new anomaly.
Everything seems to run fine except the lxc list command requires several minutes. The lxc list --fast takes about 20 - 40 seconds. I am using Version 3.16 for both client and server. lxc cluster list seems two work fine, and so does lxc exec bash.
I have not rebooted servers since this problem started about a week ago. I don’t like to reboot servers unless absolutely necessary because I have bad luck restart lxd afterward.

And now it really strange part. Sometimes it works better than others.
Any ideas…