Performance problems when adding or removing relationships between tables in a large physical Toa (4239389)

When opening a large Physical TDM v3 Model in XML Format (*.txp) and then adding or removing relationships between the entities, it takes a very long time to create the relationships and TDM seems to freeze.

Steps to Reproduce:

1. Go to menu File | Open.
2. Select a *.TXP model and click Open.
3. Remove a relationship between two entities.

Expected results:
Relationship is removed straight away and model is updated.

WORKAROUND:
Use Reverse Engineering to import the DDL extract of the database and recreate the entities and relationships.

1. Go to menu File | Reverse Engineering.
2. Select your database connection and click Next.
3. Select "DDL script file data provider" from drop down. Click Next.
4. Load DDL extract to create database. Click Next four times.
5. Select all tables from the list.
6. Click Execute.