If your hardware has reached the limits of its performance capabilities, there are a few different approaches to expanding it without adding new machines. The cheapest solution is to switch from a 32-bit environment to a 64-bit one, which can often be accomplished without buying any new hardware. If you've gone as far as you can go with software and need to scale up, there are some key upgrade points to consider for business intelligence deployments.
Note: You may need to adjust your support entitlement contract to complete some of the upgrades described here. The Pentaho BA Server is licensed per CPU, so increasing the number of CPUs in your deployment will require a higher level of service. Contact your Pentaho sales representative for more details on support plan pricing.