How to improve network speed in Windows 10 by increasing IRPStackSize

We have some folks here that are smarter than me on networking (ok most of you). I’ve never heard of this, how about you? Is it worth messing with?

This is a registry setting in the path Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters

LanmanServer is Windows networking. As in LAN, not Internet. Are you wanting to have increased performance for CIFS/SMB ? If not, I doubt this is any benefit whatsoever.


What I found depressing is that the article is all “should… should… may…”. Not once is there a “we tried it, and we got x”. That’s pretty poor tech journalism in my opinion.

Don’t get me wrong, I will probably try it as not everything happening on my network is going to the Internet, and I have a perpetual curiosity about tweaks. But it’s still pretty lazy writing, “how many words can I get out of this unverified thing I found somewhere”, and there’s no way I’d deliver something like that for publication. :roll_eyes:


That’s a stretch! Post felt like an SEO play to me. These guys have to make money somehow :man_shrugging:

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Well now, this is interesting. Ran some tests, using on a recent Acer Swift 1 laptop on a pretty vanilla install of Win 10 1909.

Before the registry change, stats from a fairly weak wifi connection were 18ms ping, 4.34Mbps down, 4.48Mbps up.

After the change, I ran 4 speedtest sequences. One ping was 19ms, the other 3 were 11, 9 & 10ms. Down was 11.37, 10.82, 9.10 & 9.90Mbps, up was 2.84, 5.64, 8.13 & 4.57Mbps.

I also had a result saved from a few days previously, using a wired connection via a USB3 ethernet adaptor - 6ms ping, 53.19Mbps down, 10.05Mbps up. Now the registry change had been made, I reconnected the Ethernet adaptor to the same USB3 socket used previously, and repeated the test. This time I got 7ms ping, 75Mbps down, 10.07Mbps up.

This certainly suggests that the parameter change has a positive effect on download speeds, possibly a slight improvement on upload as well. Haven’t had an opportunity to check if any difference on video streaming / video calls yet, but it certainly merits investigation.

As time permits, I’ll try the effect of the change on some other systems and report back.

Edited 14 Mar: somehow I transposed the “Down” and “Up” labels in my original wired connection stats - d’oh!

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