Hi Theo,

I will share some more details so that the community can be aware of why this is happening. 

The complexity of the algorithm that calculates the crossings between the shapes and connections is exponential. The algorithm gets heavy at the moment when you have a large number of shapes and connections. The engine will take one connection and iterate all elements in the diagram and check if they are crossing. If they are crossing the bow segment will be applied at the exact spot. We understand that ConnectionBridge is a good visual optimization for the end user to distinguish which connection to which shape is pointing.

Our team will investigate if there is a way to optimize this process. At the moment I have more information regarding this, I will reply here so that the community can take advantage of it.

Regards,
Dinko | Tech Support Engineer
Progress Telerik