Chips these days have monster technical reference manuals. I usually use Okular (KDE) for large PDFs, but text search is slow - as in minutes - and each subsequent search is slow.
So I tried Evince (Gnome), and it only took about 10s to search an 8000-page document. It also showed the search results in the side panel so you can quickly jump through them. Very efficient.
Okular seems to have better annotation and markup tools.
Different tools are often better at different things.