Apple quietly released iBooks 1.2.2 on the App Store Thursday.
The 14.9MB download includes a number of important stability and performance improvements, including:
- Addresses issues playing video included with enhanced books from the iBookstore.
- Resolves a problem where some books open with a different font than expected.
- Makes iBooks more responsive when navigating books with many items in their table of contents.
From : http://www.appleinsider.com/articles/11/04/22/apple_releases_ibooks_1_2_2_gree_acquires_openfeint_social_gaming_platform.html
I used to be a user of Ibooks but I find them very slow and sometimes unresponsive, so I switched to an alternative called : Stanza. I use Calibre to sync my books with stanza. Stanza is more responsive and has a hell lot of features than Ibooks.
Anyway, you may go to Itunes store for an update.