Large amount of files to parse/organize, tips on algorithm?

[cnb]

I have a bunch of files consisting of moviereviews.

For each file I construct a list of reviews and then for each new file
I merge the reviews so that in the end have a list of reviewers and
for each reviewer all their reviews.

What is the fastest way to do this?

1. Create one file with reviews, open next file an for each review see
if the reviewer exists, then add the review else create new reviewer.

2. create all the separate files with reviews then mergesort them?