How Many CPUs/Cores Pentaho Can Use?

I just migrate Pentaho BI CE 4.8 from an ubuntu server with 2 cores to an ubuntu server with 24 cores, and also big increase in other resources such as memory, etc. But I still feel latency when I access reports, analysis or dashboards in BI suite. Is there any limit on CPUs/Cores Pentaho can use?

Also can we scale out Pentaho to multiple servers, like Hadoop?

Thanks.