Performance issues like a single-node

Hi, guys;

I have a problem with performance of my sigle-node elasticconfiguration.
I have version 6.3.0, with docker

When I have the service more than a month up, I have performance problems.
I need restart service and run. but it happens again.

This is my configuration of recourses:

 --limit-cpu 6.0 
  --limit-memory 16GB 
  -e ES_JAVA_OPTS="-Xmx16384m -Xms16384m" 

any ideas?