[SOGo] SOGo memory optimizations

["Ingo D."]

We see that SOGo eats up quite a lot of memory, maybe in the end more than the
Exchange Server it replaces (32GB). We now migrated 450 named users to the
system (these users usually are not very active), and we had to increase the
memory recently from 8 to 16 GB after the system became unresponsive. Right
now it runs stable. Are there any recommendations on how the memory
consumption of SOGo can be optimized?