Thanks All, for your replies and feedback.
So, this is what I mean by "hitting the ceiling" in my projects. I don't mind waiting 5+ minutes for a project to load up.. I too have various EWQL PLAY plugins and certain Wave and IK Multimedia plugins are super taxing to load and run. What does bother me tremendously is that after a certain point, my CPU usage monitor in X2 shows the first core slamming up into the red area. What's even worse, is that upon playback the time indicator struggles to make it through the project. I get crackling, skipped sections.. awful playback.
Even if I bounce to tracks, using 100% wave files in a project, I can hit that ceiling if I get into the 15 to 25 track projects. I use busses and subs extensively to share common reverbs, compressions, etc, etc. Still very saddening to have to deal with this.
I often upgrade my Windows 7 updates. I'm never more than a month behind on those. I make Acronis Disk Images often and will load a new fresh image before starting larger projects. I am on X2a. My OS is super duper clean with no extras running in the service tray or background.. ever. I run a clean disk and defrag each time before I save a new disk image. I make a new image whenever I do a OS update, Sonar patch, even when I install new plugins; and I always load the orig image first, then make my changes and updates before making a new image.
My OS harddrive is all by itself on a Velociraptor 10K RPM HDD. Blazing fast, clean and stable. It houses only my OS and program files, nothing more. All my VST and plugins are on a striped RAID HDD set all to themselves. That drive is JUST for plugins. My projects are all yet on another striped RAID HDD setup, and that physical setup is JUST for my projects. My striped RAIDS are blazingly fast. I back them up often however just in case.
I've built my setup at an optimal setting for Sonar to live happily, but somehow it seems to want more RAM or CPU very quickly.
My sound studio workstation is ONLY ever used for music production, nothing more... not even surfing the web. Aside from Sonar, I will occasionally run other audio programs like Melodyne, Masterwriter, Maschine, CD Architect, SoundForge... but it's 90% only ever Sonar X2. And when I'm running Sonar, it's ONLY Sonar and plugins within X2.
I am often saddened when I see how quickly that first core runs into the red area.. but the other cores are all still sleeping.