General information

[The following article comes from MVP Steve Easton. Thanks a lot, Steve! The text has been slightly edited, formatted, and enhanced.]

If you have an NVIDIA video card and Windows XP or 2000, check the registry key

HKEY_LOCAL_MACHINE
 \SOFTWARE
  \Microsoft\Windows
   \CurrentVersion
    \Run

and see if nwiz.exe is being launched on start up.

If so, download, install, and launch Process Monitor (or the older, single-purpose Registry Monitor—RegMon).

With a wild card * set as the filter so that it shows everything and see if the machine is making constant registry queries looking for:

HKEY_LOCAL_MACHINE
 \Software
  \NVIDIA Corporation
   \Global
    \NVTweak
     \DisableWindowCaching

If so, either create a DWORD ValueName DisableWindowCaching and give it a value of 0 (zero) or if you're running a single monitor simply delete the nwiz.exe entry from the run key.

I don't see this issue in Vista, but then I only have one monitor.

Technical background

Because if nwiz is launched and the registry entry is missing, the system is constantly querying the registry for the entry because nwiz (or a dll it uses) doesn't properly cache the response from the query.

By querying the registry I mean for example 20,000 times just while launching Expression Web. Or a thousand times if you maximize a window and scroll the mouse across it.

Interesting enough though is the query is masked by whatever application has focus so that it appears the application is making the query.

I caught this when investigating why a program was so slow to open or even display the splash screen that I almost launched a second instance (and my machine is fairly quick).

I've posted this in another tech heavy newsgroup and had positive responses on the noticeable improvement in performance.

However, the difference won't be as noticeable in a high end machine.

Later comments

I just discovered this last week while doing some beta testing.

Thought it was an application issue, and the dev team was all over it like ants on a gumdrop in the grass in July. They were happy when I posted the cause and solution. Quote:

That's terrific news. I'm sorry you had so much trouble with this but it's nice to hear that this time it's not our fault. And even better to hear that you have a fix. If only the rest of our problems could be so easily solved. :)

I've Contacted NVIDIA about it and gotten no response (as of yet).

I would recommend to actually check using Process Monitor (or RegMon) before making any registry changes, although adding the registry ValueName is totally harmless because if not needed, it is ignored.

It is not written up anywhere that I could find using Google to search for: DisableWindowCaching. If you search it now you will get 3 valid hits, all posted by me.

Unfortunately I didn't take any screenshots while chasing this down, but I can always unwind the fix and take some.

Also fwiw, I had some [people from a certain big software company] over at the [...] groups verify this with positive results.

nVidia nView Desktop Manager

[By MVP Jon Kennedy—thanks for the good info!]

Nwiz.exe is part of the software packaged with nVidia drivers that includes the nView Desktop Manager. I always disable this from starting up using msconfig.

Since having to put in new hard drives, I'm using the Dell OEM drivers, and this "feature" is not installed on my system currently. (A search turned up no nwiz.exe.) If and when I decide to update my drivers, I'll have to disable nwiz.exe from starting as I've done in the past.