Hello Andrew
Unfortunately there have been other changes: php was upgraded from 5.4.x to 5.5.38.
I am just surprised by the sudden explosion of connections.
When something changes so drastically i like to find out if that behavior is expected.
If someone with knowledge of the codebase knew that for example now a new set of data is kept
in memcache that would be a perfect example. But this could also be a sign of a bug:
Connection to memcached getting closed and reopened multiple times during one request.
But since all seems to be working (banner get delivered, statistics are created, etc) and Server seems
to be fine with the load i calmed down.