The nexserv.exe process is started when the CCSVM console is started. It may be observed that the nexserv.exe process is consuming approx 75% or physical RAM even when idle.
It's normal for CCSVM to use all of the available memory allocated for JVM. The online help states: "The host that is running Symantec CCS Vulnerability Manager uses all memory allocated to the Java Virtual Machine (JVM) for scanning and for any Nexpose system functions. This is important to keep in mind when using RAM to optimize scan performance."
It is possible to reduce the amount of RAM used by JVM by editing the NeXposeEnvironment.env file; you could for example change the line '-Xmx${max-mem}' to '-Xmx1536m'. Save the file and restart the CCS Vulnerability Manager Console service. With this setting in effect, you should see that the physical RAM usage is reduced.