Microsoft's roll-out of Windows 10 gets under way in earnest on Wednesday, and with so many Windows users likely to want the upgrade, Internet performance could bog down at times this week.\n"Windows 10 ... will easily be the largest day\/week of traffic ever on the Internet," said Dan Rayburn, a Frost & Sullivan analyst who weighed in Monday on the Web traffic snarl on his StreamingMediaBlog.com. "...Windows 10 is going to create some serious havoc with regards to the user experience. Expect to see some download times in the days, not hours, especially if any other content owners happen to have larger-than-expected traffic at the same time."\nIn short: "Quality of service for downloads could deteriorate really quickly and remain poor for days, if not longer," Rayburn said.\nTo try and avoid problems, Microsoft is stretching out the Windows 10 release. Here's how that works:\n\nWindows Insiders who have been beta testing the OS since last fall will get Windows 10's final code first. Other users will get Windows 10 in what Microsoft has called "waves," though it has not defined how large those groups will be, when they will get the upgrade, or how long it will take to push Windows 10 out to everyone.\nThe Redmond, Wash. company will quietly pre-load the upgrade on Windows 7 and Windows 8.1 devices whose owners have already "reserved" copies. After the code has been completely downloaded to the PC or tablet, Microsoft send an alert telling the user that it's ready to process.\nMicrosoft has reserved up to 40Tbps of capacity from multiple content delivery networks (CDNs), including Akamai, EdgeCast, Level 3 and Limelight Networks for Windows 10's distribution, Rayburn said. The expected surge in download traffic will likely still flood many ISPs' capacity at "interconnection points" where the ISP's network connects to the Internet backbone or to other carriers. "ISPs already know that their interconnection points in some cities are going to be overloaded," said Rayburn.\n\nAlthough the expected slowdown of Windows 10 downloads might not be obvious to most users because the upgrade is being delivered in the background -- the congestion means it'll take longer to deliver the OS to all of the users who want it.\nSaid Rayburn: "I've never used the term 'break the Internet' because most of the time people say that, they are simply overhyping an event on the Web. But with the volume of downloads that Microsoft is expecting and the capacity they have already reserved to deliver the software, the Internet is in for some real performance problems this week."\nWith reports by Gregg Keizer at Computerworld.