Yes, this is true. Page turning time is about 2 seconds.
As I understood from the comments of the author of the FB2 plugin, it is the problem with the EInk display driver - for some unknown reason, it takes more then half a second after sending page to driver and before page flipping starts.
The only suggestion I can propose is to use native WOL format. It seems, that page turning is much faster with it (and there is
great FB2->WOL convertor software, you can prepare a book with you favourite fonts). But as the disadvantages you'll get huge files without the possibility to change font size "On the fly".