Improve region filter performance by pregenerating tables

Description

Closes issues: Related issues:

Converts subqueries to temporary tables. No logic changes.

Type of change

• New feature
• Breaking change
• Bug fix
• Improvement

Testing

• Tests have been added that prove my fix is effective or that my feature works
• Related tests have been modified/removed

No test changes needed.

Database

• Includes changes to database schema
• Includes necessary database migrations

Configuration

• Includes changes to configuration
• Includes configuration migration instructions in documentation

Other

General

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My branch has recently been updated with new changes in dev before this merge request
• I have made corresponding changes to the documentation