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Tweak your Windows settings for faster Web access

May 27, 1998
Web posted at: 1:00 PM EDT

by Steve Bass

(IDG) -- Ever hear of the MTU? Nope, it's not the Boston subway or the music video channel. It's an obscure setting in Windows 95's Registry, known mostly to people who use pocket protectors.

But don't let that put you off. Tweaking the MTU (Maximum Transmission Unit) can double--and in some cases even triple--the throughput of your Internet access in less than five minutes. And for an unbelievable price: free.

How does it work? Prepare for a little geekspeak. Data shoots across the Internet and into your computer in packets. The packets are sized for optimal transfer speed over Internet backbones, routers, and ethernet networks. But if you're connected through a modem and an Internet service provider, this default packet size is less than optimal. The result? A substantial performance hit because the packets are fragmented and need to be reassembled.

Naturally, I'm going to point my finger at Microsoft. The computer giant obviously wasn't paying attention when it set the MTU default to 1500 in the Windows 95 Registry. Lower that number to 576, and your throughput will increase substantially. This MTU fix is almost as good as squirting some WD-40 into the back of your modem. (PC World's lawyers warned me to say I was just kidding about the WD-40. Kids, please don't try this at home.) Even Microsoft has admitted that the change is useful and has repaired the problem in Windows 98.

Don't doubt that changing the MTU makes a huge--no, humongous--difference. In a Bass Laboratory blind study, I changed the setting on my wife's system without telling her. Touching her machine is risky (fortunately, I'm insured against spousal computing disasters), but this particular death-defying act paid off. She asked if I had changed ISPs or had done something to her machine, because her favorite Internet sites seemed to be--and I quote--"coming on-screen lots quicker than usual." Ta-da!

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The Big Fix

You don't need to wait for Windows 98 to fix your MTU speed. With nothing more than Windows 95's RegEdit, a free tool that's probably already on your hard drive, you can make the change in a few minutes. (Except, of course, for my Mom. Please, Mom, don't fiddle with the Registry, okay? I'll do it for you the next time we're over for dinner.)

But don't mess with the Registry just yet. First, back it up with Microsoft's free Configuration Backup utility. That way, if you wreck your system somehow or screw anything up, you can always restore the old settings. You already have a copy of Configuration Backup--it's on your Win 95 CD-ROM in the Other\Misc\Cfgback directory. If you can't find the disc, download the program from, part of PC World Online.

If you're Registry savvy, you'll find that there's nothing to it. Use RegEdit's Find feature to search for MaxMTU, pressing to repeat the search if necessary. Once there, right-click on MaxMTU in the right pane, choose Modify, and change the Value Data to 576. Then close the registry, reboot the system, and get ready to fly.

Presto Change-O

If RegEdit can't find a MaxMTU setting--or if you feel at all confused--don't worry. You can download one of several great MTU presto­change-o utilities in minutes. All of these will make the MTU setting changes for you, and they're available at

The easiest of the programs to use--and the one I recommend--is PPP-Boost ( It's free, and the interface takes no special skill to use. If you want to do some extra tweaking, try Mike Sutherland's $10 MTU-Speed Pro 4.10 ( Finally, for a mere $15, you can try Patterson Design Systems' TweakDUN 2.0 (, the only program in this excellent trio that includes built-in help.

The technical details on MTU are available on what I consider the premier MTU site, NetPro NorthWest's Techfile at

Okay, that's the scoop on MTU. Now it's your turn. Tell me your Internet speedup tricks at

Contributing Editor Steve Bass is a licensed marriage and family therapist and the president of the Pasadena IBM Users Group.



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