Here are some further observations:
I was wrong in assuming, that memory consumption starts at about 5Mib/sec,
actually it starts very slow and multiplies with every new started game. After
10 minutes or so, it already has claimed 2 GiB of RAM, after about 30 minutes
it has filled all RAM and 10
Public bug reported:
When started, gnome-mahjongg uses appr. 0.43 % of my 4GiB of RAM. After making
the first move it begins to claim more memory until it gets killed by Linux
"out of memory". It's memory "consumption" lies at about 5MiB/sec. After some
games this rate rises. It happens all the