Some configuration options will provide better performance, while others will increase the load on the BMU.
Bridges are all handled in software and don’t have particularly high performance. You should expect to see higher than normal CPU usage if you are passing a lot of traffic through bridges. While the limit of usage on a bridge is going to depend on the overall utilization of the BMU and the model of the BMU in question, it is generally recommended to keep traffic on bridges as low as possible. Use routed interfaces whenever you can.
When configuring address ranges in Powercode, performance will be higher the more specific the ranges are. For example, if you are using 10.0.0.0/24, 10.0.1.0/24 and 10.0.2.0/24, it is much better to define those three address ranges individually rather than simply defining 10.0.0.0/8 and placing all equipment entries in that larger subnet. The BMU can hash packets against individual subnet lists and limit the amount of processing that has to be done when address ranges are more specific.