Lately I've been trying to find out why my cpu usage is high on moderate sized projects and last night I found one of the culprits. I discovered this by starting a new project and importing broadcast wav files from a current project in order to have a clean slate, free of plugins in order to find who the cpu hungry vsts were.
 
The project is a 24 track audio (44.1/24bit) only and with no vst's loaded it plays at 64 buffers and barely moves the cpu meters. I then loaded 5 instances of CA-2A on some vocal tracks and at that point the CPU usage rose to about 25%!! Not the plugin I wanted to see. The CA-2A is hands down my favorite compressor and I usually have an instance loaded on all vocal and guitar tracks. Bummer. Just for comparisons sake, I replaced the CA-2A's with Waves Renaissance Vox and the CPU impact was low/minimum. I much prefer to use the CA-2A. I also noticed my graphics were hay-wire/glitchy in console view with 5 prochannel strips showing with the CA-2A's loaded (jumpy or stalling transport module). Disabled the CA-2A's and all was well.
 
Anyone else see CPU impact like this using the CA-2A?
 

Are you using the regular vst instance of the ca-2a or the pro channel version? I use the pro channel (pc-2a) version, and I use a bunch of instances on my projects which normally have 32-35 tracks and 8 busses at 24bit/44.1k and I never see that kind of CPU usage.

I tried both with the same results. 
 
Thanks for responding - I'm thinking of uninstalling and re install ca-2a. I have more than one instance of that 64 bit plug show up in the plugin manager. Maybe something is wrong there...

musicroom
I tried both with the same results. 
 
Thanks for responding - I'm thinking of uninstalling and re install ca-2a. I have more than one instance of that 64 bit plug show up in the plugin manager. Maybe something is wrong there...

Having it installed more than 1 time doesn't have anything to do with CPU usage. It has to be inserted and enabled in a Sonar project for it to use any CPU.
 
You need to take into account your sound card, its drivers, the driver settings, the sample rate, your PC specs, w and your MOBO.  
 
For starters, just raise your buffers from 64 to 96 or 128. This will relieve your CPU. Depending on your sound card, you may need to raise your ASIO  buffers. 
 
Some sound cards and PC's can get away with having it at an ASIO buffer of 64 and some cannot. There are too many variables within your PC and sound card drivers.  you may have too many programs running in the background and it may just be that your PC cannot handle it. 
 
CJ
 

Hey CJ - I was thinking more in terms of a corrupt install as a possibility vs multiple installs. I do hear you though. I normally mix at much higher buffer sizes, I had the buffers set this low to find out which plugins are accumulating so much cpu power. I may find others that I use a lot -- but, I was surprised to see the CA-2A be one of the more cpu hungry ones.
 
This daw is and has been a good one - but it is getting a little old. Hopefully I'll have Jim R. build me another one before much longer. 

You should be able to run A LOT of CA-2As on a Q9550! No idea what the problem is though...

SvenArne
You should be able to run A LOT of CA-2As on a Q9550! No idea what the problem is though...

 
Thanks Sven, I normally have a lot of them loaded (around 15), but I have the buffer size set to 512 and all is well. I was surprised that 5 instances with no other plugs loaded in the project would cause such an increase...
 
I may try the uninstalling / re installing to make sure nothing is corrupt with the ca-2a. Probably not, but it's worth a try.

Update: Not sure what is going on with my system but I ran this same project experiment using the same parameters in Reaper 4 and the cpu usage was at 1.11%, no glitchy graphics, etc. Reaper hardly seem to notice I was using it.  I guess I have something wrong with either my X3 install or my Win 8 install. I may wait a few weeks, but I thinking of doing a system wipe and re-install.

Update: All is well now. Clean Win 8.1 OS/Sonar install was the cure for X3 operating lean and mean. Thanks to all for your suggestions.

Yeah that worked for me not so long ago .... :) Good call!