> I will try to optimize the table indexing the headline field as
> suggested. One question regarding this: Can this be done from rails or
> are these mysql commands ('CREATE INDEX' etc.)?


Yeah, you can do it from Rails migrations:

http://apidock.com/rails/ActiveRecord/Migration, section 'Available  
transformations':

add_index(table_name, column_names, options):
Adds a new index with the name of the column. Other options  
include :name and :unique (e.g. { :name => "users_name_index", :unique  
=> true }).

Cheers,
Peter