Just to close off this case, the final SQL that SET was looking at is "slow-ish" because it has to make at least 2 hits to the DB (maybe even 4?) because at least 2 of the fields are BLOB SUB_TYPE 1 fields, which I have learned require multiple hits to the DB. Without those fields included in the field list, the query is < 1s.

I need to include those fields and the slower response time is tolerable if I explain it to my customer.

-- Side note --

During my 22 years of experience, I have had excellent response times ( < 1s) on all properly made queries, using multiple tables and JOINs of various kinds, on both/either VARCHAR() AND INTEGER fields, in any/all the major RDBMSs.

To stuff everything in 1 table defeats the purpose of using an RDBMS. It's not "wrong", but, just not what RDBMS was intended for.