In general, NetVizura performance primarily depends on the inherited number of counters (nodes) and number of users you want to monitor. End User traffic does not significantly affect CPU and HDD usage. However, it may have impact on:
DB write time increase
Shared Syslog database increase
Depending on the RAM availability it increases it more or less (when RAM is less available it can increase by only a couple of percentages, when RAM is more available it can increase up to 100%).
There is a way to optimize NetVizura RAM usage by increasing Tomcat memory. Read more about it under "Tomcat Memory Allocation" section within specific NetVizura Installation article.
DB Write Time Increase
In environments with more than a few hundred End Users, DB write time can have a noticeable increase. This can significantly degrade application performance (slower displaying of charts, delayed triggering of NetFlow alarms, loss of data).
This can be solved by changing PostgreSQL configuration. You can find out more about it within NetVizura Installation article under "Tweaking PostgreSQL" section.
Shared Syslog Database Increase
If you use also NetVizura EventLog Analyzer, End User syslog logon messages share database storage with the rest of syslog messages and might increase disk usage thus triggering removal of old syslog messages sooner.