Most people are happy with 150-200dpi, although if you have a 13 inch tablet you might want to run some tests around 200+.
600 is too high I think.
I often scan at about 300 and keep those files. Then downsize to 150 or 200 and use those. This way, I have enough resolution for any tablet in the future (hi-res screens, size etc.) because I will not have to scan from the books again (I can either batch process the original files or just use those).
Yes you are right, the bigger the file, the longer it will take to load.
Also crop out the white margins to save file size (unless you need the page numbers as reference) although you could add the page numbers back in where necessary using annotations in MS or Acrobat (or similar) somewhere after you have cropped.
600 is too high I think.
I often scan at about 300 and keep those files. Then downsize to 150 or 200 and use those. This way, I have enough resolution for any tablet in the future (hi-res screens, size etc.) because I will not have to scan from the books again (I can either batch process the original files or just use those).
Yes you are right, the bigger the file, the longer it will take to load.
Also crop out the white margins to save file size (unless you need the page numbers as reference) although you could add the page numbers back in where necessary using annotations in MS or Acrobat (or similar) somewhere after you have cropped.