If SQL Source Control takes a long time to refresh when you open the Commit or Get latest tab, you can try the following troubleshooting options:

• You can reduce your log detail level - logging is known to impact significantly the performance of comparison
• You can disable auto refreshing

You may also want to consider moving to Flyway, which is Redgate's new x-Database DevOps versioning and automation solution.  Since it supports over 20 databases, it's not integrated into SSMS, which means that we're not limited to the SSMS processing space.  We've also reduced the number of comparisons we run to also improve performance.  Learn more.