With all the problems Windows is facing, I think one area where Microsoft can make some easy, quick gains is by drastically improving Explorer, Windows’ file manager. It seems that in the latest developer releases, they’re doing just that. The most impactful change – possibly – is that Microsoft is going to preload Explorer.
We’re exploring preloading File Explorer in the background to help improve File Explorer launch performance. This shouldn’t be visible to you, outside of File Explorer hopefully launching faster when you need to use it. If you have the change, if needed there is an option you can uncheck to disable this called “Enable window preloading for faster launch times” in File Explorer’s Folder Options, under View.
↫ Windows Insider Program Team
Microsoft is also reordering the context menu in Explorer, and while this may seem like a small set of changes, the new context menu does look much tidier and less busy. They achieve this by moving a few top-level items to a submenu, and reordering some other elements. Sadly, the context menu still retains its own context menu (“Show more options”), which is a traditional Win32 menu – which I still think is one of the most Windows of Windows things of all time.
Regardless, I hope these small changes make Explorer more bearable to use for those of you still using Windows, because we all know you need it.

I can’t even come up with a comment about this: It’s too egregiously crap.
I never thought Explorer was all that slow, even on an extremely slow machine.
Why don’t they make it run RIGHT, instead of FAST?
I think we are back to Windows XP times. (Which also preloaded stuff)
And, no, the Explorer does not need to be preloaded. It is not doing much more work than what it did in XP/Vista times. (But no, it is doing more than those lightweight ones. It really is a heavy lifter).
But… to be honest, there is only one feature I know of that makes a real difference:
Proper isolation of extensions. Up to Windows 10, WinRAR and others injected their icons by directly living in the Explorer process space (COM/ActiveX). Now they are separated.
But is it the reason of slowdown?
Of course not.
Look up: Win UI 3