Hello Peter,
Yes, I know it, and the destroy method is also called during the routing. However, from the js heap snapshot, we can find ‘jqx._jqxGrid.prototype.definedInstance’ still reference to the scope, which will cause the scope can not be destroy. Furthermore, the ‘definedInstance’ is extended on prototype, this is why I think we should release this reference manually.
I think the test case can reproduce this issue, maybe try first 
Thanks in advance.