It seems de rigueur to complain about Emacs being slow on Windows or even, according to some, on every OS. It’s easy to throw out such aspersions but a lot harder to offer solutions.
RobThorpe over at the Emacs subreddit does have some suggestions. His first observation is that often the problems aren’t Emacs’ fault. His example is Git. It turns out that Git itself is slow on Windows and it doesn’t matter if it’s being invoked by Emacs, some other editor, or the command line; it’s always slow on Windows. There are other applications like that on Windows and elsewhere.
RobThorpe’s recommendations aren’t limited to, “suck it up, it’s your OS’s fault”, however. He offers several actionable recommendations that will help regardless on what OS you are running Emacs under.
One such piece of advice is to not turn on what you don’t need. That seems obvious but it’s easy to end up with functionality you don’t—or no longer—need enabled. That may be because you used to need it but no longer do or because a framework such as Doom loads it even though you’ve never used it.
Another point he makes is that most users don’t really need to reload Emacs all the time. I’ve said this over and over and it’s the reason that I don’t care at all about my Emacs load time (even though it’s relatively small). Most experienced Emacs users keep it running all the time even if it’s in demon mode. I don’t even bother with that. I just have an Emacs instance running all the time in a separate (OS) window.
The post has a few other suggestions and the comments also offer some good advice. Mostly, the differences in speed are undetectable to a human user so I’ve found it best not to obsess about them but if you’re seeing a lot of latency, take a look at RobThorpe’s post for some suggestions for improving matters.