Archiving / Unarchiving Best Practices

[bassangler]

I have 2 questions about archiving:

1. How "big" does a forum need to be before you should start archiving?  Is there a threshold, say post count, where you start to see performance improvements?

2. How do you "mass unarchive" posts?  For example, the past 5 years.

[Downzy]

I didn't want to start a new thread on this as others have already asked.

I run a forum where a large portion of the forum had to be moved to a non-public area due to conflicts with Adsense's content policies.  

My goal was to move threads to a public section of the forum and keep them organized on a year by year basis.  But to move the archived threads to a separate section, I have to unarchive them each individually.  There are 775 pages of archived topics.  With 25 topics per page, that's 19,375 individual topics that need to be unarchived in order to be moved.  I had been unarchiving them individually but it's too much and need a faster way to do this. 

Any recommendations or help would greatly be appreciated.

Thanks!