What would you suggest as an alternative viewer? Things I like about it is the index that shows, as with datasheets, and the ability to highlight easily and save with highlights.
On Windows, I've been using PDF XChange Viewer for a long time. Great stuff with all features you'd likely ever need. The free versions are full of features already and no annoying spyware/nagging/updaters.
Otherwise, one open-source alternative that is now really good and that I'm starting to use more and more, even on Windows, is Okular. Eons above Sumatra PDF IMO.
https://okular.kde.org/Binaries there for Windows:
https://binary-factory.kde.org/job/Okular_Release_win64/You can download the 'okular-xxx-windows-cl-msvc2019-x86_64.7z' archive. No installation needed, just extract it, the application is 'okular.exe'.
(otherwise available on pretty much all Linux distros.)
It even handles digital signatures of documents.
One thing I particulary like is that it automatically reloads PDFs modified outside of Okular. Very handy when you work on documents that are generated as PDFs, such as if you work with LaTeX or similar. PDF XChange Viewer wouldn't even allow writing a PDF if it's currently opened in it, which makes it annoying for this use case.