SVN commit 259045 breaks -CURRENT

I noticed a severe slowdown and network problems on my amd64 -CURRENT
system. By bisecting SVN revisions I identified the following commit
to be responsible:

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r259045 | kib | 2013-12-06 22:44:13 +0100 (Fri, 06 Dec 2013) | 9 lines

Disallow optimizations which potentially remove boundary checks
for signed values due to a compiler authors considering integer
overflow as impossible.

The change follows suit of other projects taking the same measure.
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This commit added the following line to /sys/conf/kern.mk:

CFLAGS+=       -fno-strict-overflow


The most obvious symptoms of the problem on my system are:

1) sa-spamd needs > 140 seconds to start
   (instead of a few seconds)

2) SSH logins are very slow, many seconds of delay between connect
   and password prompt, several seconds after password entry until
   a command prompt appears (normally instantaneous)

In general it takes many seconds to open a TCP socket, even to
localhost.

I can perform further tests on this system, but it will be a lot
of work to locate the source files that are mis-compiled with
-fno-strict-overflow.

I'm surprised that nobody else seems to be affected by this problem,
since it is very obvious on my system and clearly caused by the
above mentioned commit.

My kernel configuration is a stripped down GENERIC plus ZFS, IPFW
and LINUX emulation. I can provide full details and a kernel that
exposes the problem on request.

Regards, STefan