One of the new core technologies in Mavericks is called "App Nap" and as its name implies, an application that is not visible or apparently active will "nap" or go into app-specific "sleep", wakened when it's brought to the front/visible, etc.
Get Info (Finder command Command-I) has the ability to "disable app nap" in its General section near the top of the Info window, so Mavericks gives users the ability to disable the feature on an app-by-app basis. Checking the box disables the napping.
Would it be advisable to disable App Nap for Fusion, of any version? I could see use for this, say that a nap might disable something like an overnight Windows Update, Windows Backup, virus scan, or other nighttime maintenance task. Or would such a scheduled task wake the app from the nap without having to go to that end?
To QuiSait: I do not in any way claim to have "the solution", but here are things I've done (I hope to get them all):
1. Keep Windows, Fusion, and OS X updated.
2. Prevent App Nap (I know that's the title of this thread, but it's still useful to have it in this list here.)
3. Allocate a minimum amount of memory and processor cores to the Virtual Machine.
In Fusion 5, it may be possible to allocate more cores/RAM to the VM, but with Mavericks/Fusion 6, less is more.
It looks like more RAM and processor cores are needed for the Fusion application and Mavericks to actually work
efficiently and it's through that that functions can be streamlined.
4. If you don't need them, disable shared folders. You can still drag/drop between the Finder and Windows Explorer in
either Single Window or Unity mode. Copy/Paste when using Full Screen may also work.
5. If you don't need to, do not set Fusion to open Mac documents with Windows apps. Use this only if you must have a
document opened with a Windows app by double-clicking in the Finder. Alternately, drag from the Finder to Windows
Explorer and open from there.
Those last two I gleaned from other threads in this forum. #3 came through observation as I found I couldn't keep Windows
running with anything more than 1 GB RAM on a 4 GB machine. #2 - well, that I discovered by accident and wanted to
share that one without delay.
Perhaps Apple will one day update Mavericks to tone down some of the core technologies mentioned at
Apple - OS X Mavericks - Advanced Technologies either at the behest of a user (a Core Technologies pane on
System Preferences similar to Prevent App Nap in an application's Get Info window) or automatically disable
when a charger is connected).
None of “the above” had any noticeable impact for me, but everything is working great again…
Unfortunately, I cannot say “how” or “why”. The only thing I consciously changed (for other reasons) was the removal of Mac Keeper. But in the mean time I am sure there were Important or Critical updates from MSFT and/or minor updates from Apple.
All I know is everything is fine again (and I’m too busy to deep dive on how/why).
I have never touched MacKeeper, but it's entirely possible that there's something going on there. An ongoing Mac process or app that's not running within Fusion can still tax the Mac system.
I've been running Fusion 6 since it was released, with a Windows 7 VM. It worked fine and as expected under 10.8. Now with Mavericks the VM goes completely unusable every night. I've disabled App Nap which helps for the most part but if I go away from the VM too long it stops functioning and I have to restart the machine. Once restarted everything will work again. I should mention that even the shutdown now takes a solid 8-10 minutes. Watching processes, it seems that the .vmx is where the hanging is occurring so I wonder if there isn't a bug either with Apple or VMware in that disabling AppNap on the Fusion App isn't being propagated to the sub processes started after the app has launched. In some ways this makes sense since can't you run a VM without the Fusion app actually running at all? I don't expect Apple to change their core functionality but there certainly is something going on that isn't working as expected in this use case.