For some time my Dell laptop (i5-8300H 2.3Ghz) has been very sluggish when I've been using PFPX to generate flight plans. It was frustrating as I couldn't work out what the cause was.
Yesterday I found the culprit. NGFMSAgent.exe running to advise of updates to their AIRAC updates. It was easily the most demanding executable in Task Manager. But why? I had already installed the latest AIRAC data. Looking at settings I had the Notification slider at 6 hours. I'm not sure why I would need it to check that often especially when Aivlasoft's EFB show a warning when a new cycle is required.
So I've stopped this program running at Windows startup and PFPX (plus everything else probably) is now much better with no pauses or apparent lockups.
If you have a FMS Data subscription maybe consider stopping it running continuously which doesn't seem logical.