I’m rendering the attached simple text epub, but it seems way slower to navigate than in a pdf (like 100ms between page turns) on a 3Ghz CPU.
Could be possibly true for other non-pdf files too.
using SumatraPDF-3.2-install
Well it didn’t allowed me to upload sample file.
Also it doesn’t allow me to select text in epub (I’m the one who like to play with text selection while reading), or even copy anything out of it. Copying works in other readers.
Test rendering speed with the latest daily build from the download page (you can use the stand-alone portable version that will leave your installed one unaffected). If you still face the same problem you can create a new issue on GitHub and attach the file there, or if it’s too large you can add a link to the file that you’ve uploaded elsewhere.
Before reporting something a quick search of the forum and Sumatra’s GitHub issues list is always helpful. See this topic for more: