I think this is a very dangerous subject, to judge by the animosity provoked by previous threads on the relative merits of Windows or Linux.
However, it always seems to me that once a Windows user, always a Windows user, and thus failing to see the merits of a possible change. But of course, what you use is entirely your own decision.
Gary has a good point about a change to an SSD as the boot drive – they can make the boot drive much faster than the old mechanical drives – one disadvantage {maybe} is that they are not usually available in the large sizes of the mechanical drives {yet!}
Another issue which slows machine booting is that all OS's (Windows, Linux, whathaveyou) start background processes during booting, allegedly to improve operating speed. Often some of these processes are unnecessary, so one thing I always do is go into the startup and stop the unwanted processes from starting. I admit you need to know what you are doing, but there is information available online how to do this, if you want to learn more – there are enough people posting on this forum who can answer specific questions as well..
Gaunless also makes a valid point – Linux has been very easy to use for several years now, thanks to the efforts of the developers of Debian, Ubuntu, Mint and others, and its free: you can even try most versions out from a USB stick, without having to install it., and as Gaunless says, LInux nowadays not only supports older computers, but has support for the latest machines, and uses much less space on the disk.
Please note that I make this post in the interests of informing people who may not be aware of alternatives – I have no wish to fire up the usual fanatics.
I know several people who eventually gave Linux a try, and never went back to Windows.