I haven't touched a Windows system in a few years, but when I worked as a Windows admin / programmer, SumatraPDF was my PDF viewer of choice. It does what it's

I haven't touched a Windows system in a few years, but when I worked as a Windows admin / programmer, SumatraPDF was my PDF viewer of choice. It does what it's supposed to do, does it well, and it doesn't get in my way while doing so. No subscription or cloud bullshit. And like you said, it's really small and fast. To top it all off, it runs without an installer, you just drop the executable somewhere and you're good to go; so people can use it without having Administrator access or bothering / arguing with their IT department.