10000 nodes are a lot but not enough to make the tree slow by themselves, first try to find more information about your problem, use the monitor and profiler to get a better guess of where is the issue (it could be in process, events or something else).
In any case you may need to optimize your design with a system of chunks/zones/cells with groups of nodes that are enabled or disabled (in or out of the tree) with certain conditions, but what to disable will depend on what are those nodes doing and where is the bottleneck.