Hmmm... uninstalling norton didn't seem to fix/change anything. Still getting pops/clicks when playing this bluray. I can see the cpu usage spike when it happens.
That's good. Then it wasn't Norton, so long as you rebooted once more after completely removing it (that last reboot makes sure the system starts "clean" without the kernel drivers from the AV application still running). Assuming you did that (and the uninstallers usually make you), you can reinstall it if you want. Norton 360 is certainly not "well respected" as being the most well behaved AV application out there. But, it should be possible to get it to behave generally with MC (if you have issues, which it seems not in this case) with something resembling these steps:
http://wiki.jriver.com/index.php/Taming_Symantec_Endpoint_ProtectionNote that you almost always have to separately exclude filesystem locations (primarily the MC Library itself, and its AppData locations, not necessarily the media file storage location)
AND the individual running processes. In fact, the latter is more important than the former, in most cases.
But, as I said, your particular problem seems to have been ruled out as being caused by Norton in this instance.
Otherwise, it might be best in a new thread because this thread title isn't really applicable anymore, but if you want recommendations on improving performance, we'd need:
* What kind of hardware do you have?
* What OS is it running?
* What drivers do you have installed for the GPU?
* Are you testing with decrypted discs, or are you running an on-the-fly decrypter (it could be some issues with that process)?
* What settings do you have enabled in MC (especially under
Tools > Options > Audio,
Options > Video, and the DSP)?
* Did you mess with any of the default madvr settings (assuming you're using ROHQ)?
Convolution filters and resampling, in particular, can beat on your CPU if you have an underpowered one. The GPU settings could also come into play, especially if you've done anything to customize madvr.