Craig,
The only problem with your analogy is that the last three times I lost the keys, they were never in the Living Room and two sets are still missing.
 
The computer performs the same with either on board video or graphics card.  This is not 1996, the vast majority of graphics cards play well with others.  This is a dedicated DAW which I have played some games on, but none are currently installed.  I got the video card so I could use three monitors.
 
I tested the Firewire interface vs the USB and I'm getting lower latency, better utilization with the firewire (was using the usb), however even with firewire adding inserts increases cpu.  
 
This mobo has a good firewire chipset and native PCI slots, and really low DPC latency, some of the reasons I have not upgraded.   This setup is at the lowest latency allowed with reported 3.7ms round trip latency.  I can obviously increase buffers but the surprising point is that simple audio routing, the External Inserts and the Channel Tools plugs, use significant cpu in sonar.
 
At higher buffer settings I am able to load up projects with 80+ instances of assorted plugs, many of them heavy.  This computer is enough for my needs; my concerns are more around operation at low latency and my disappointment that routing plugins use significant CPU.
 
 
 
 
 

Interesting. My RME UCX measures lower round trip latency with USB than Firewire. I tried it. Even RME says faster with USB, but shrug.
 
Maybe something special about your set up ... ?
 
Round trip latency is measured in the preferences somewhere if I recall. You can see the numbers.
 
I don't know why you get the processor spike.
 
I wonder if you add a whole bunch more instances of external send does it keep going up?

The reported RTL (3.7ms) is the same with the USB, but cpu utilization is a bit higher (?), so I can load more instances at lowest latency using the firewire.  I am using the onboard usb2.0, but I also have a usb3.0 pcie card which may influence the usb in some negative way.
 
I'm using Firewire for a couple other reasons.  1) Less likelihood of usb bottleneck or interruptions from other devices.   2) When I direct connect my GT100 for online editing, I get a tiny ground loop noise when the UFX is connected via usb.
 
Yes, I am using the UFX for mix verb and mix bus compression.  I was going to use the External Insert, but routing the send out a stereo bus and using loopback accomplishes the same thing.  I have thought about doing the same with track compression and EQ, or using the UFX as an external mixer, but the Pro Channel is sufficiently lightweight that I can mix ITB.
 
What RTL is sonar reporting for your UCX?
 
 
 

I am not savvy with external inserts, but am wondering if the low latency is contributing to this. If being used for mixing (not tracking), does bumping up the audio buffer a notch or two help?

Using a higher buffer setting decreases cpu utilization, but adding an external insert still shows a noticeable uptick.
 
The whole point of using an external insert is to offload processing, so this surprises me.

My UCX Latencies are in this post
http://forum.cakewalk.com/FindPost/2967987
Firewire
69 samples input
126 samples output.
195 samples round trip
 
USB
76 input
93 output
169 round trip
 
You might be interested in these two videos I made a while back.
#1
https://www.youtube.com/watch?v=7xR29K5hdBE
#2
https://www.youtube.com/watch?v=mAMp9MPAj3k
 
Basically, the idea is you use the ADAT to loopback all the channels so you can stack the FX if you want.
 
 

200bpm
The whole point of using an external insert is to offload processing, so this surprises me.

There may have been times when I would have seen the whole point as to provide a method to offload processing, but I haven't seen it that way for years. The main purpose is to use any external equipment. Consider re-amping. Or use of some hardware compressor. If the only purpose was offloading processing, I wouldn't need it at this point.
 
I'll bet you Mr. Craig Anderton uses external inserts pretty casually as do any number of other regular users.
 
For me the real value is that it auto calculates the latency offset through the external equipment and compensates the whole mix appropriately so that you don't have problems introduced by the round trip latency (exactly what would happen if you just send it to your outputs on your interface and then route it back in. Now, on your interface at lowest latency, I'm not sure you could hear it. If your track ended up 69 samples behind or something. idk who cares. In that case I'm suggesting that you are looping back inside your interface to take advantage of the fx processor in your interface.
 
For that matter, you could get 0 sample latency offset if you send out both the instrument mix and the one item for external fx, then loop them both back and re-record them together or mix them together in the interface before loopback and record the combined pair. idk. Just thinking. In other words, they'd both have the same new latency introduced which would mean it wouldn't matter.

I can try cutting the latency way down to see if that produces a noticeable spike. But yes, gswitz, I do use external inserts quite a bit and never noticed anything iffy, even with the two-core 2.4 GHz Vista laptop or the ancient dual Athlon i had years ago.
 

200bpm
The computer performs the same with either on board video or graphics card.  This is not 1996, the vast majority of graphics cards play well with others.  This is a dedicated DAW which I have played some games on, but none are currently installed.  I got the video card so I could use three monitors.

It's not about the card, it's about the "HD Audio" driver which is indeed installed in 2014 by many, if most, graphics card software packages. Its purpose is to send video out to an external TV. It is unnecessary for audio work and for its intended purpose, no one cares if sound goes to their TV 20 milliseconds later. But we do.
 
At least humor me, disable that driver, and see if it makes a difference. If it doesn't help, you've lost two minutes. If it works, you'll see a decrease in latency-related problems. This driver operates independently of your RME but not of your CPU.
 
Also check for updated graphics drivers. Several people who have had problems in these forums had them go away magically with new drivers (but after you install them, remember to disable the HD Audio driver).
 
I'm not saying this is guaranteed to solve your insert problem, but it could very well have other benefits.

Is the PC specified in your signature "AMD PhenomIIx4 @3.6, HP Pavillion DV7-7012nr" the machine you are experiencing problems with?
 
I ask as I note that it is a marketed as an Entertainment Notebook PC Product and I wondered how you changed the graphics card as indicated in earlier post. 

I just set the ancient two-core Vista laptop to 10 ms latency with 32-bit MME, which caused it to flip out and stutter because it couldn't cope. I inserted four external inserts and made sure the meters were working their butts off. No difference in CPU consumption. I also did things like turn the double-precision engine on and off, and set bit depth to 64 bits, but the external inserts just didn't make a difference. I've spent a couple of hours on this and that's enough, so I officially give up trying to duplicate this problem. I can't. So far it seems like no one else has, either.