The books I use to practice typing are in Chinese. I noticed that when there are too many characters in a paragraph, there will be lag and unsmoothness.
Currently path is used to identify a book, which means if you have the same epub in different paths, it is detected as different books. I think it should be changed to be identified by checksum, so that they are detected as the same. That way the save will be the same for both, and you wouldn’t have the same epub loaded twice if you have it in two different locations in library search paths.
So far i am loving this tool! Just writing to ask if you could add a San-serif typeface such as Roboto or Ubuntu or a font selector as an option, I may try myself but I've never used PyQT5 and i am unfamiliar with the codebase.