Unfortunately, This behavior is normal. WPM is very CPU intensive and we've had to build a server farm for our WPM players.
We found the WPM player agent was running multiple transactions at the same time in parallel. This would result in the periods of the CPU being overloaded in a cyclic fashion. Any time the CPU would max the playback response times would be affected of course. In an effort to force WPM players to run the transactions serially. I reduced the number of worker processes to a value that matches the number of CPU cores and set max playbacks per worker to 1. This forced all playbacks to run 1 at a time per worker and settled the CPU activity.
Edit: C:\Program Files (x86)\SolarWinds\Orion\SEUM\Player\SolarWinds.SEUM.Agent.Service.exe.config
The two properties you want to modify are:
numWorkerProcesses
maxPlaybacksPerWorker
Save and restart the WPM services on that player.