CURRENT slow and shaky network stability

[O. Hartmann]

Since a couple of days now, FreeBSD CURRENT (at the moment with FreeBSD 11.0-CURRENT #9
r297267: Fri Mar 25 09:48:07 CET 2016 amd64) "feels" a kind of shaky and like "glue": it
is slow with X11, sometimes ssh connections even nearby hosts on the same net not under
load have some time to respond to keys in xterm or on console (vt()) ~ 1 - 3 seconds and
I receive very often "broken pipe" to ssh connections to a host nearby. I realized this
strange behaviour on a couple of systems a maintain running most recent CURRENT. 

I also realize a high usage of swap on a 8GB RAM, 2 core box having two ZFS volumes (one
3TB HD and one 4 TB HAD with ZFS). Using Firefox on X11 (nVidia 364.12/355.11 driver, I
checked on both) and running desktop only (windowmaker) brings the system toward using 12
or sometimes several hundreds of megabytes of swap - and I do not see what is using so
much space.

Does anyone also realize  this phenomenon?

Regards,

oh