Ruby or compiled?

I'm trying to decide to take a 6 year old, very extensive application written in PHP, C sharp (mostly) and Perl and migrate the whole damn thing to Ruby on rails. This is an application that has an extensive MS Sql backend and searches TB's of text very quickly. No one in our industry supplies an open source solution so we would be first in a 6B + industry, of which, I have a miniscule percentage. My concern is that the compiled code runs very quickly and our customers require very fast searches across hundreds of thousands if not millions of records and I'm concerned the interpretive nature of Ruby will not perform as well. Testing that postulate will take a lot of effort and I'm worried of that cost if it is not as effective. I realize there is much more knowlegde of our app required to make a definitive decision but I'm leery of revelaing too much of our market on a public bulletin board. Any insights from a 60k foot view?