This if my first mod, I've first seen the "giantbook.xml" and though, hmm... what if I tried to dummy the file and test if the books would not appear on the game at all? And the result, it worked.

This will remove animations for:

Books like, Book of Belial, Revelations, etc.;
Mom's items, such as Mom's Pad and Bra;
Any rune animation;
Eternal Hearts/Black Hearts/Rainbow Poop*
*There are variations on this mod that can re-enable those*

Keep in mind that your character will suffer a small delay, since the game is trying to load an animation on the "giantbook.xml" file, and the item is associated with that animation. Removing the lines related to the "anm2root="resources/gfx/ui/giantbook/" will cause the game to simply not load.

This was made without the Afterbirth expansion, it should work with Afterbirth however, but I do not own it to test it. I tested this only with The Book of Belial and the Whore of Babylon.

The Isaac's Wikia states that the "Whore of Babylon" animation can be disabled with the "pop-ups" option, but nothing happened (it only disables the "YOU HAVE UNLOCKED" messages).

I have no idea if the "pop-ups" option affects those books in Afterbirth, but still.

The mod includes some variations, the first, "Everything Removed", removes every animation from it. The second, "Hearts and Sleep" will keep the animations for the following: "Getting two eternal hearts (or going on a floor after getting at least one", "Hourglass animation, kept since the boss "Death" uses it", "Black heart, so you know the enemies will be killed after taking damage", "Rainbow poop, so you know you've got all your red hearts back, and "Sleep, which I think is the one used on the Bedroom sequence". The third variation, called "Just Sleep" will remove everything except the sleep animation.

Thanks.