In order for the v3 Active X control to determine what updates were needed, the entire list of available software on Windows Update was downloaded to the user's computer when they visited the Windows Update web site.
As the number of updates offered by Windows Update grew, this resulted in performance concerns.
For previous versions of Microsoft Windows, users can download updates from the Windows Update website, using Internet Explorer.
Windows Vista and later provide a Control Panel to configure update settings and check for updates.
The Windows Update Control Panel also has the function of downloading Windows Ultimate Extras, optional software for Windows Vista Ultimate Edition.
Arie Slob, writing for the newsletter in March 2003, noted that the size of the update list had exceeded 400KB, which caused delays of more than a minute for dial-up users.
Windows Update v4, released in conjunction with Windows XP in 2001, changed this by having the Active X control submit a list of the hardware components to Microsoft's servers, which then returns a list of only those device drivers available for that machine.
It also narrowed down the list of available updates for the operating system and related components by sending details of what operating system version, service pack, and locale are installed.
German technology web site published an analysis of the Windows Update communication protocol in February 2003, which received wide attention on technology web sites.
A link to Windows Update on the Start Menu gave access to additional downloads for the operating system.
At the time of Windows 98's release, Windows Update offered additional desktop themes, games, device driver updates, and optional components such as Net Meeting.
Microsoft routinely releases security updates on the second Tuesday of each month (Patch Tuesday), but can provide them whenever a new update is urgently required to prevent a newly discovered or prevalent exploit targeting Windows users.
System administrators can configure Windows Update to install critical updates automatically so long as the computer has an Internet mobile connection, without the user needing to install them manually, or even be aware that an update is required.
Windows 95 and Windows NT 4 were retroactively given the ability to access the Windows Update website, and download updates designed for those operating systems, starting with the release of versions of Internet Explorer 4 for those operating systems.