Hi,
This was also affecting 7.920 and a few versions back that the master node in the cluster appears to be suffering from a memory leak when HTTP/S proxy is running as evidenced from the increasing memory utilisation (pic attached).
When the proxy is off or in standard mode, this condition is not seen.
Ulrich - you may recall this from about a month ago when the system was suffering from this condition.
I'll continue to monitor this and will post updated stats tomorrow.
Cheers,
Darren