I raised case with NetApp and this is what I received as answer, (but this is not acceptable for us).
"In our software we create a connector per storage object to make parallel operation possible. Therefore, also with fewer controllers and high count of storage objects you could reach a high number of connectors.
What could be done?
If you have more servers, you could spread the workload by adding servers to the pool and to add some controllers to other management servers. If you have more than 1 they should appear under management servers."
The issue with slow alert view and right click is because "Forward to" option which search through all the connectors.