Why is reading PDF files on Safari of OS X 10.8.4 still blurry?

This is my first time use of Mac laptop. I have 15" inches MBP with retina display. The Safari on older OS ( i do not remember the version number) has superb PDF reading experience. I thought it would be better with latest OS update but it is on the contrary, the texts r blurry even using Apple's original browser. I need to use Preview ( which i dun feel like a stand alone PDF reader). Acrobat X still doesn't support PDF files on retina display. Do you guys hv any idea? i m a college student, i purchesed Retina mainly for reading ebooks.