My system is already maxed and have already hit the wall with programs R and Matlab so I need something brutally fast at strings/IO

In that case, try my suggestion of renting a server somewhere to do this for you. Digital Ocean is a popular one, and their prices range from USD 0.007/hour for 512MB of RAM to USD 0.952/hr for 64GB with a 20-core processor. One of their big selling points is that when you're not using it, you simply "turn it off" and don't pay anything.
You get a virtualised Linux instance to do whatever you'd like with.

Amazon also offers their "EC2" service which is essentially the same thing -- but beware of large corporations trying to lock you in!
HP has one as well, I believe, as does Microsoft.

In your opinion/experience the grep will be faster?

I really couldn't say. The most largest array I've grep'd was maybe a few hundred members.