Excellent lightweight and pure Win32 software, always finds its way into the system whenever I need to visit MS-land. Never change, and please never do a "modern" electron.js hell rewrite, Sumatra PDF is an exemplar of something that does its job and asks only for what it needs.
This reader along with 7Zip, IrfanViewer, FreeCommander, Gvim (and some others) comprise the old faithfuls.