Me either. Galbanum uses more cpu for me. Could you post exact steps that I could use to reproduce? A midi file? Does it only happen on record or also on playback? Are the samples installed on the same drives? Are you maybe having memory or IO issues?

Have you contacted support?

Do you have a gpu?

I haven't yet contacted support because I was certain that this was a simple settings error on my part, or some easy fix.  The ONLY other thing I can possibly think of is hard drive latency.  All of my Cakewalk files are installed into the default C: drive locations, but I'm using a Samsung 850 Evo 250GB SSD.  That should be fast enough to handle a single instance of RPro, right?
 
GPU is an EVGA brand GTX980ti.  
 
It happens on MIDI playback and live input with my Akai MPK61.  When I record audio, the pops happen during the recording, but are not present when I listen to the audio.

Steps to reproduce would be load RPro into a simple instrument track using the Atmospheric>Liquid Orchestra 1 patch.  Play some 3 and 4 note chords.  The popping sound is happening right when I change chords, at what I would assume is the instant that the sample is being reloaded.
 

All samples are loaded into memory with the program in all Cakewalk sfz based synths. The synths do not rely on streaming audio samples.

Well there went that idea.  :)  Thanks Scook!

That particular patch has 6 elements each with 72 voices.
 
This means that they may stack and overlap and press your processor (back me up someone?).
 
http://stabilitynetwork.blob.core.windows.net/g-tunes/20160621_Test.wav
 
I tried playing at 48 kHz and 96, 256 and 512 with that patch...
Atmospheric>Liquid Orchestra 1
That patch has 6 elements each with 72 voices.
 
I could get above the patch's ability to fit under my processor ceiling even at 512.
 
The hold pedal mattered a lot. Laying off the hold pedal I was able to play most things.
 
Once on the hold pedal I was able to glitch it.
 
Even just a harsh attack on the guitar I could glitch it if I hit the guitar fast.
 
I would surpass the number of voices my PC could support.
 
I'm not sure if this information helps you.

Try clicking on some of the elements at the top of the Synth and click the drop down and choose 'unload'.
 
Then see if you still get the clicking.

Really, I think you are just overloading your machine.

I'm not so sure that I'm overloading my system, but I'm open to learning.  

Using the Atmospheric>Liquid Orchestra 1 patch with 72 voices active across all 6 elements, the max single core CPU usage is only 33% according to HWmonitor.  I understand it's an extremely complex patch, but it's happening on many others as well.  Unloading elements doesn't get rid of the popping, even if I take it down to just a single active element.

Here's a link for the MIDI I'm using right now.  I have Sonar's tempo set to 120 and I don't use a sustain pedal.  https://www.dropbox.com/s/l5qgcfloa2zclyj/test.mid?dl=0
 
What I don't understand is why I have to increase my audio buffer so much, and why RPro is the only plugin I have that gives me this issue (specifically the RPro library sounds, not the legacy sounds).  Especially considering that I've got other synths that will overload my CPU which work fine at low buffer settings (no pops).
 
At this point I've done an entire system wipe and reinstall of everything using CCC.  I only have RPro installed so that there is no conflict with RSession or the two legacy synths.  

It's disappointing because I really wanted to like RPro.  If I'd paid the full retail price I would probably be asking for a refund.  Kontakt or Omnisphere are looking like they might be a better investment at this point.

Me with Rapture Pro tonight.
 
http://stabilitynetwork.blob.core.windows.net/g-tunes/20160624_01.mp3
 

I'm still hoping this is an example of "Jackroller doesn't understand how to use his equipment," and that someone will come along with a definitive answer so I'll know what I'm doing wrong.  I've emailed support, but I'm still trying to figure this out.

Could Firewire drivers be to blame?  I'm using the latest MOTU driver for my interface, but the pci-express firewire card it's connected to is just using the default Windows driver.  
 

@jackroller - I need to apologize in advance here - but your forum profile picture is leading me astray:
 
Could it possibly be that aliens have somehow caused all of this?  Possibly some alien technology - a living organism based on a binary sequencing of alien DNA?
 
I am REALLY sorry - I just found your profile pic really really funny and couldn't help myself.
 
I DID read through the thread, and have not yet come up with any ideas on why this is happening to you.  I will go fire up some fresh coffee and take another spin through and see if anything makes sense.
 
Bob Bone