MacPro constantly shuts down / kernal panics after High Sierra upgrade

Part of me suspects a hardware problem, just because this is not a panic cause I normally see.

However, there are some 3rd party kernel extensions, and they are always our first suspects

com.paceap.kext.pacesupport.snowleopard	5.9.1
com.Apogee.driver.DuetFWOverideDriver	1.4.4
com.focusrite.driver.FocusritePCIe	4.6.1 236

If you do not need them, you might consider removing them.

Or boot into Safe mode, which should not load them, and see if the panics go away.

http://support.apple.com/kb/ht1564

This will not load any 3rd party additions, it will load some more conservative Apple drivers (may cause screen flicker), and it will clear some kernel caches (a cache is saved data in a form that can speed up a program, but is totally redundant to the original source, and thus can be safely cleared).  Booting into Safe mode is just an experiment, but can frequently eliminate any 3rd party interference, or a cached item out-of-sync with the world.  (Verify Safe mode via Applications -> Utilities -> System Information -> Software -> Boot Mode -> Safe vs Normal)

Runaway user process - A user process is using a large percentage of your CPU.

Open Activity Monitor Find what is using so much CPU & force quit it.

Delete thisfile ^ restart...

~/Library/LaunchAgents/co.iristech.Iris.plist

~ tilde indicates hidden Home Library.

Apple hid the Users' Library folders...

Method 1:

1 From the Finder, select the Go menu at top of the screen, and choose Go to Folder.

2 In the window that opens, enter ~/Library, and click Go.

Method 2:

1 Go to the Finder (or desktop).

2 Hold the Option key on your keyboard, and click the Go menu at the top of the screen.

3 With the Go menu open, you'll notice that pressing and releasing Option will display or hide the Library choice in this menu.

4 Select Library from the Go menu (while holding down Option) to access the hidden folder.

Safe mode does load more conservative drivers, so sluggish can be one side effect.

Upgrading macOS can cause a kernel extension that worked with a previous kernel to break. Some kernel extensions do not play by the rules, and access stuff in the macOS kernel address space that they should not. If the new macOS version changes things inside the kernel, the kernel extension can now step on something unexpected.

If you can uninstall the 3rd party extensions and see if the panics stop, that would tell you it was a kernel extension. If the panics continue, it is not the kernel extensions.

At the minimum, make sure you have the kernel extension versions that are compatible with your version of macOS.

Gulp, unresponsive processor sounds like hardware, but post a report from this App...

EtreCheck is a simple little app to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac.

http://www.etresoft.com/etrecheck

Great news.:)