[REGRESSION] Fresh CURRENT consume much more CPU on network traffic (vlans + routing + ipfw with NAT)

 I have "SOHO" router on Atom D2500 with FreeBSD CURRENT. It runs
CURRENT for very long time (from 11-CURRENT times), and recently it
start to consume much more CPU on same traffic — to the point when it
becomes unresponsive in shell (via ssh, not local console).

 I have rather complex ipfw ruleset, but this ruleset is the same for
many years.

 Revisions before r333989 worked normally, I never seen any problem with
shell, no matter how much traffic is processed

 Revision r334649 with same configuration, same firewall ruleset, etc.,
becomes completely unresponsive under network load (pure transit traffic).

 when system is unresponsive I see this in `top -SH`

100083 root -76 - 0K   272K -       1 291.8H  95.31% kernel{if_io_tqg_1}
100082 root -76 - 0K   272K -       0 297.7H  95.20% kernel{if_io_tqg_0}

 And it is new to me.

-- 
// Lev Serebryakov