server eats quite a lot of ram

[kotc]

server cmdline: java -jar JSettlersServer-2.7.00.jar

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
24447 root      20   0   11.4g   8.2g  19028 S   0.0  26.6  41:44.12 java

it was running for a few weeks with occasional games, ~1-2 per day.
it's a private one that i'm only using with my gf. i know it's java, but 8GB ?

after restart:
23481 root 20 0 11.4g 74380 18444 S 0.0 0.2 0:00.60 java