It would be very useful to be able to correlate the server performance reported by APM ( appdex / request per minute / execution speed ) with app / system performance metrics that aren't currently collated (e.g. CPU % , available/used memory )
e.g. the sort of thing I think can be found in new relic and application insights because they monitor the server as well as the application, although you might argue it is out of scope of the Raygun APM agent as it isn't strictly related to the application trace , but a very useful metric that would compliment this if it were captured.
I think for a start the ability to send performance metrics like these along with the raw trace data when it is captured , then it could be seen in the raw data tab, which could help to learn whether current system performance might be causing a slow trace. If this were rolled out to all APM agents then the APM section could include a graph of average CPU / available memory to compare against the existing metrics.
Background: We have a number of IIS ASP.NET Framework applications (websites) running on shared Windows VMs outside of our control so we don't have access even to the VM metrics, but we have managed to have Raygun APM agent installed on them. Now when site/performance issues are raised we are able to review some traces (a selection due to sampling) but not able to see if either the server was having performance issues at the time , nor which of the applications (if any) were causing high CPU/memory , and it isn't a metric that you are able to see after-the-fact , e.g. to open task manager and check the CPU of the w3wp.exe for each site)