This behaviour is expected and perfectly good for video rendering. If you have a multi core machine (and if Pinnacle is multi core aware), you can go to task manager, right click the process and set the affinity to only a few cores.
However, I would leave it at 100% if I was you - would you rather run the CPU at 50% and it take twice as long?
Personally, I would also check for antivirus and see if you can exclude Pinnacle's temporary folder and whatever folder it is saving the file to as that may make a big difference (and if it doesn't lower CPU, it could increase speed heavily).