On Windows, software installation/removal involves a deep analysis of machine configuration state. This takes time but accounts for the high probability of binary compatibility between the operating system and third party software of arbitrary functionality and variable engineering quality that might be a decade old.
The Windows software system has different tradeoffs than Linux where distributions are compatible with specific versions of software -- i.e. if the distro doesn't have a package there may not be binary compatibility. With Linux changes to the kernel can require cascading upgrades to packages or make packages obsolete or break packages.
Windows' tradeoffs are also different than those made by BSD and similar systems that eschew binary distribution --- systems where everything gets compiled from source on the user's machine. In terms of speed, compiling a large application from source can take significant time though it will probably require few if any reboots.