Confirmed: Vista Bug Slows Network Traffic While Music Plays
Mark Russinovich, a major Microsoft techie, today acknowledged a bug with Vista's network programming that can noticeably slow down file transfers on a local network if you play music at the same time.
Vista prioritizes media playback to try and make sure that your music and videos play smoothly even when your computer is busy. It's a nice feature I've written about previously, since without it, you can get annoying pauses and playback glitches if you're running many programs at once.
But forum posters and bloggers recently noticed a serious slowdown in how long it takes to copy a file across a network even when the PC wasn't busy when Windows Media Player, iTunes or Real Player was running. In a detailed post today, Russinovich said it's due to a bug that hits if you're on a high-speed (1Gb) local network and using a computer with multiple network interfaces - such as a laptop with wireless and wired connections.
Russinovich writes: "there?s an unfortunate bug in the NDIS throttling code that magnifies throttling if you have multiple NICs. If you have a system with both wireless and wired adapters, for instance, NDIS will process at most 8000 packets per second, and with three adapters it will process a maximum of 6000 packets per second. 6000 packets per second equals 9MB/s, a limit that?s visible even on 100Mb networks."
In Russinovich's testing, that translated to transfer rates of less than a third of what he got without WMP playing (6 percent throughput on a 1Gb network with WMP versus 20 percent throughput without).
The slowdown will still be noticeable but not as bad on a 100Mb network, he says. And even without the bug, the Vista feature when working normally will still throttle file transfers down to about 15 percent throughput on a 1Gb network.
But you shouldn't notice any slowdown for Internet downloads. Russinovich writes that "despite even this level of throttling, Internet traffic, even on the best broadband connection, won?t be affected. That?s because the multiplicity of intermediate connections between your system and another one on the Internet fragments packets and slows down packet travel, and therefore reduces the rate at which systems transfer data."
No word yet on when we might expect a bug fix, so if you're copying a lot of data between Vista PCs at work or at home, you might want to turn off your tunes for the duration.
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Dude my rate is horendously slow. I am only trying to play 1 film through my regular network. When I attempted to access the file where is was at it took 48mins to finish loading. Granted I do have a lot of files but I would never guess this would be happening like this. When I finally am able to view my film it plays slow and stops and goes and stops and goes. Anyone have any suggestions. Oh, yeah when i view the files straight from my External through my desktop it plays fine. I only have this problem with my Network. Music plays fine once it gets going. Email i cranberyy22@yahoo.com