Improve a SQL query (stored procedure) that runs very slow

Job ID: 35812572

Budget: $10 – $30 USD

I have a database, programmed years ago by someone with no current contact.

One set of data is piled on a table (currently 10 million records, Table-1)
With that data, it updates a book's DB, divided between Main and Detail.

When processed a record, that record is moved to another table (currently 3 million records, Table-2),
and deleted from Table-1

The script runs extremely slowly. hard/soft config.
i3 4Ghz - 16 GB RAM - 120 SSD - Win 10 dedicated - Xampp nonproductive environment

Execution time is something like 100 records every 5 minutes, resulting in a never-ending script.
I would like to (start your response with the word TurtleSql or it will be ignored) improve this procedure.
Related categories: SQL MySQL Database Administration