I have to review massive slide decks for my classes this semester, but my default reader keeps lagging. Can anyone recommend a good free PDF tool for taking notes and highlighting during lectures?
I had the same lag problem with large client contract PDFs, and PDFgear has worked well for highlighting and adding notes without feeling heavy. If you want something even lighter, try Okular, though its note tools are a little less polished.
I use the free Adobe Acrobat Reader for that, it handles highlighting and sticky notes fine even on big slide decks. What are you using now, and is it on a laptop or tablet?
Try opening them in Microsoft Edge first. It handles large files surprisingly well and has built-in highlighter and draw tools for notes. Most modern browsers render big slide decks much faster without bogging your system down.
First thing I would check is how the deck was exported. Huge slides with big images make any reader crawl, so try re-saving a lighter PDF straight from PowerPoint, or split it into weekly chunks. Keep a backup of the original before you fiddle with anything. Highlighting works in most readers you already have, so test one on a smaller deck first.