Any ideas on how I can do load and performance testing on SQL Server 2012's merge replciation?
We do replication on millions of records per day. And so we have a requirement to measure how many records it can replicate over a period of time.
As an additional challenge, it will be great if we can simulate having 1000 or more subscribers, and emulate the bandwidth of the subscribers.
This will allow us to measure project proposals even before making changes.
I haven't tried this yet, but you can check out Zen4Sync, Orchestration and Test Load Platform for SQL Server Merge Replication, ymmv.
The performance will really depend on your network, hardware, and database design. Some guidelines for enhancing general performance are covered in Enhance General Replication Performance. There is also some good tips in Enhance Merge Replication Performance and Merge Replication Performance Tuning and Optimization.