Many 1000s of URL redirects in Drupal 7: PathAuto/GlobalRedirect, apache .htaccess, or another solution?

I am looking for the 'best' (fastest, most efficient) way to map http requests when there could be as many as 30,000 different URLs that need mapping.

I have made a map pointing URLs on the old vBulletin system to the URLs on the new Drupal 7 system.

My question is how to do the rewriting. I cannot use Apache mod_rewrite and RewriteMap since my server admin does not allow it. I prefer not to write a custom module. So I am looking for the best (most scalable) Drupal module or another solution.

I would assume PathAuto and Global Redirect would be the way to go but I want to know if there are scaleability issues with so many URLs in the map.

Apache mod_rewrite's RewriteMap reads the map and stores in memory until the file's mtime is changed -- does Global Redirect do that?

Edit: I do not have access to use Apache's RewriteMap directive, but I could place the redirects in an .htaccess file -- would that be cached in memory, or looked up on each request?

Thanks!

Turns out there is no problem with tens of thousands of URL aliases using the modules

Redirect Global Redirect PathAuto

I imported the aliases with Redirect Import (but ran into file upload size limit).