(Only for developers familiar with apktool. I'm distributing neither the original nor the hacked version of the Google Books APK.)
I was annoyed with the eink-refresh flickering caused by Google Book's page-turn animation, so I attempted to remove it. The result is a modified app in which turning a page at least does not flicker, but admittedly still is a bit slow.
I do not intend to further enhance or support the modification, but I'm posting it here for the enjoyment of others. The patch applies to a apktool-decoded Google Play Books 1.5.4 app (the latest version still running on the PRS-T1), but a similar change is possible for older versions of the app.
One complication in rebuilding the APK is that the contained resources.arsc file is too big for the PRS-T1 to uncompress. The solution is to store it in the APK file uncompressed. Here's what I did to the apktool-built APK file before signing it:
aapt r Google_Play_Books_$VERSION.hacked.apk resources.arsc
aapt a -0 '' ../../../Google_Play_Books_$VERSION.hacked.apk resources.arsc