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Whenever I show the Network tab of the Windows Resource Monitor in Windows 8 my wireless network performance decreases by 50%.

I was trying to work out why I was not getting anything more than 150Mbps on an 802.11n network and thought I would use the Resource Monitor to get feedback but whenever I show the Ui network performance dips from 21MB/s to 9MB/s as in the graph below.

The red bars highlight the dips that occur when restoring the window:

speed kills

If I open Resource Monitor and minimize it the effect is nil but the moment I show/restore the dialog my network performance dips to < 50%.

Is this a known issue? Seems utterly ridiculous to me. What's the point of the tool if by merely using / observing it you drastically alter the performance characteristics of the thing being observed?


Perhaps I should also add this is a new chip Intel 4770-K with on-chip graphics, no discreet card just yet. Don't see why that should make a difference unless I'm an Intel guinea pig.

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Just to be clear, I photoshopped in the red bars. They're not Windows UFOs or anything. –  rism Jul 11 '13 at 14:24
I'm guessing that one of those is a network drive? –  Moshe Katz Jul 15 '13 at 19:00
By the way, note that 150Mbps is the best you'll get if you only have one wifi antenna. To do better, you need a card with 2 or 3 antennas. –  Moshe Katz Jul 15 '13 at 19:01
My first guess would be that the very act of displaying data causes the slowdown because it means that Windows has to inspect the data instead of just shoveling it through. It would be interesting to see if you have any speed reduction if you run WireShark during the transfer instead of Resource Monitor. –  Moshe Katz Jul 15 '13 at 19:03
@MosheKatz Camo is a desktop system and Steel is a laptop. The drives being directly connected (internally) to each. I've got an ASUS Maximus Vi board which come with an on board MPcie combo card with dual anttennas so I think I should be covered. If you guess is correct then I would never want to see a progress dialog given the drastic effect it has on transfer. I cant see why Windows would need to inspect the data, i thought all these graphs were driven off WMI anyway. –  rism Jul 16 '13 at 6:48

1 Answer 1

Although the following statement comes from the resource monitor for SQL Server, the statement is still prevalent to your situation:

As with all performance monitoring tools, expect some performance overhead when you use System Monitor to monitor SQL Server. The actual overhead in any specific instance depends on the hardware platform, the number of counters, and the selected update interval. However, the integration of System Monitor with SQL Server is designed to minimize any reduction in performance.

I'm pretty confident that with the fact that your system has an integrated graphics, your CPU is sharing the load of displaying the necessary data for the resource monitor as well as making the actual transfer of data.

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This can hardly be an issue. Do you transfer your data using smb right? I don't think this happens for everybody. I suggest using some other network monitoring tool to verify the speed while opening network monitor... –  Vitas Mar 17 '14 at 6:50
@Vitas I'm not sure if you're responding to me or to the OP. However, I still stand firm that this is probably a slight dip in performance from CPU overhead being used to display the updated info. –  KronoS Mar 17 '14 at 21:37
KronoS that would be a case only if the CPU was at 100% from some reason. Transfering data over smb should not be CPU intensive unless there is some strange problem. It reminds me the old times when some hard drives had problem with DMA mode and worked only in PIO. It used a lot of CPU when doing I/O operations... –  Vitas Mar 18 '14 at 12:23

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