The Plugin DSP Load window is helpful in cases where some of the plugins in use overload the CPU, resulting in audible clicks and pops in the output, but you aren't quire sure which ones are causing this exactly.

For each plugin in use, there is a chart and numeric data that represents minumum, maximum, and average CPU time used, as well as standard deviation. This, along with simple color coding — green for safe amount of CPU use, red for CPU overload — gives you a good overview of what's going on in the session.

You can use this data to decide whether you want to replace a plugin with a less resource-hungry one, freeze a track, or report a potential bug to the plugin's developer and wait for an update.

It's worth noting that certain type of plugins, like convolution reverbs and guitar amp simulators, tend to consume more resources.