[Stunner] Editor is opened slowly when process is big

When you have a bigger process that contains 10+ nodes, its opening takes about 20+ seconds compared to 4 - 5 seconds it takes for old designer to open it. Processes with lower amount of nodes seem to be opened constantly, however there is difference when you use Catching intermediate events, with those the process opening time is increased too.

This behavior (slow opening) increases with increased number of nodes in editor.