I've been hit by panda 4 (40% decrease). I didn't see any change during panda 1-3. From what I've read it and when compared to my site, the change is probably due to the fact that I have over 30M pages indexed on Google, and they've starting seeing that as some sort of bad indication. Although I feel all of the pages have a unique value that Google should crawl, it seems I should make some tough calls and deduce the indexed pages according to some prioritization I will conduct. The question is what should be my target, or what factors should help me figure out a relevant target.

How many pages should I try to reduce to?
- 25M
- 15M
- 1M
- 2000

Is it enough to add noindex to low priority pages or should I also remove all internal linking to them?