Does the internal Calibre reader convert PDF files?
I suspect that the internal Calibre ebook reader converts PDFs to a different format for display. This is because much formatting is lost, yet one now has the ability to resize the fonts and change the font faces. Additionally, one of my CPU cores goes to 100% for a good minute or two before the PDF file opens.
Is there a way to have Calibre open the file in it's native PDF format, or should I continue opening the PDF files with Okular?