>If you have the disk space, you can replicate the memo field as an all-uppercase clone and search on this. It will speed things up just a bit by avoiding the UPPER() function.

Actually, I mean you need to replicate both your original table and memo file, but the replicated table only needs to hold the primary key used in the original table. Replicating a memo field for the original table will double the size of its memo file and make the searching go slower.