If you make some manually generated crash dumps while the problem is happening, we can probably use that to see where the CPU is being used:
You can also use Process Explorer to find out if it is Opus itself or a third party DLL causing the problem. Right-click dopus.exe, choose Properties, then Threads. Sort the threads by CPU use and select the top one, then click Stack. The list of DLLs can be used to see what is using the CPU. Do that a few times and post the screenshots of the stack window, and we may be able to see just from that.
This guide may also be of use, but more if you cab identify which tab the problem happens in: