I have IDCS5.5 and 6. I had in .id file which was done in CS3 opened and saved in 5.5 I need to convert to epub. I'm working in 5.5 using the articles window and I'm in the process of anchoring the images in. The book is 300 pages but I'm just setting up and checking a test for one chapter.
I notice that after converting the css file is HUGE! With all the text overides and fonts. Since from what I read and see, the fonts will default to the readers fonts and my concern is the book has alot of italics used in quotes, bold text used for names etc. In the test epub I see these styles are retained and need to know if I should be concerned with the large css file slowing down the ebook itself?
If you're using InDesign's CSS, there definitely is unnecessary code there. You can use the techniques that Anne-Marie Concepcion talks about in her Lynda.com videos and that Elizabeth Castro talks about in her ebooks to pare that down.
Or you can create your own CSS file.
Nonetheless, I've never heard that a large CSS file would "slow it down."