[chrisn]

I have the same problem, except I know exactly which book is causing it. It is Art Of Agile in EPUB format from Oreily books, which I purchased directly from them.

The Kobo will eventually finish loading the book (it takes about 15+ mins) but then even reading it is exceptionally slow and basically it is unusable.

I used Calibre to do a EPUB->EPUB conversion, which actually made the file size larger, but it allowed it to load in about a minute instead of 15 (still slow but bearable). Changing the font takes a long time and is broken through (Will try running the font fix after Calibre instead of before it this time). It also broke the chapters.

This EPUB is perfectly readable in ADE and Calibre, it passes the validator, there is nothing at all wrong with it. If the firmware release tomorrow does not fix this it is going straight back to Chapters and I'm placing an order for a Kindle. No company should ever be allowed to release something as broken as this is.

Edit: Actually something that could be a factor is the book has a lot of chapters organized in a hierarchy. The Kobo isn't displaying all of these chapters or the hierarchy, perhaps it is just too much for it?

Edit 2: Ok performing these steps has had the best result so far:

1. Add the epub to Calibre
2. Peform Epub -> Epub conversion in Calibre
3. Run the resulting epub through the font fixer

I can now load in a reasonable time and fix the fonts. This book has 63 pages of chapters (683 chapters) basically because it has a lot of individual section which are being interpreted as chapters and the Kobo has no concept of the hierarchy (a pretty glaring oversight if you ask me). My best guess is this is leading to some of the loading slowness, if anyone knows how I can use Calibre to cut out some of the chapter marks for the sub-sub-subsections that would be appreciated.