If you're running VMWare Fusion in debugging mode, I have to imagine that every time you start up the virtual machine, you see a warning message that says you're in debug mode and explains how to disable it to improve performance. Then again, if you always have the VM running, perhaps that never shows up. Or you have "click ok already" syndrome where you just click on buttons to get the $#@$ windows out of the way without actually reading what the message says.

No worries, it turns out that you can turn on higher levels of debugging and logging in VMWare Fusion, though I imagine that it's really only useful for people within the company since I would have no idea how to find the log files or what they meant, personally.

The only nuance is that you can only change this sort of setting in your virtual machine if you have the actual VM shut down. In other words, if you're running Windows, you need to choose "Shut Down" before you can change the settings of the VM itself.

Here's the window I see when I start up Fusion if my VM is in debug mode:

Maybe you checked the "Never show this dialog again" button which is why you don't see it any more? In any case, the directions are pretty straightforward, though since you have to close the window to proceed, it's hard to remember. That's why I'm here!

If you don't pay attention and go to "Settings..." under the "Virtual Machine" menu, you'll get here as always:

You can see the "Advanced" settings icon, it's the gear on the bottom row. Click on it if you've still got your VM running, however, and you see this:

It's the "Troubleshooting" entry you want to change, but it's greyed out. Because you still have a running virtual machine. Oops.

Shut off your VM within the guest operating system (for example, choose "Shutdown" from the Start menu in Windows) then when you see the triangle superimposed over the main window, go back to "Virtual Machine" --> "Settings..." and choose "Advanced". This time your option will be selectable, and here are the options:

Wondering what they all mean? VMWare explains:

I chose "None" and restarted the virtual machine and it seems to run faster, though it's hard to gauge exactly how much performance improvement there is without some sort of benchmark or diagnostic software.

In any case, that's something you'll only have to ever tweak once and it'll be part of the configuration of that virtual machine forevermore. Hope that helps you out!