Hello Bridi,
Generally the java processes got a high consume of resources (ram, cpu). EPAgent have a use equilibrate of the resources, and improvements from one version to another higher. By my experience how developer, the major use of recourses is on the plugins. On our customer, we have a best performance with Perl plugins over Java plugins, even though it also depends on what the each plugin does.
We have a windows server with only one agent (EP) with a one java plugin, but this plugin generate over 80000 metrics. And this server always is generating alerts, by exced both cpu and ram use.
On the other hand we have a server with 30 EPAgent, some with a single plugin and others with more than one plugin (perl plugins), more other applications running (CA ADA) on the server and see alerts of use of cpu and ram is litle probable.