There are a handful of tables in the database but one of them is about 80% of the data and another is about 15% so those two tables hold most of the data.

As for the fill factor, I had it at 100 when I last rebuilt it because the database is read-only.

I've been rebuilding all of the indexes in my testing mainly because the only indexes not fragmented are on tiny tables. Both large tables have 90%+ fragmentation after shrinking the DB.

The growth factor is set to 1GB I could lower it, but I assume that would only save me at most 500MB.