[Geremia]

I notice that when ebook-reader is open, the graphics (such as switching virtual desktops) really slows down. I don't have these issues with any other apps.

Also, ebook-viewer run stand-alone from the commandline is much faster at loading books than ebook-viewer launched from within Calibre by hitting "v" key. "Loading book, please wait" takes less than a few seconds, compared to several seconds.