Developers of J2ME support for NetBeans did measuring of the JDWP traffic, because excessive traffic makes mobility debugging problematic.
They have found that right after the attach, there is a lot of traffic related to class prepare events. It was found that there are two related requests created in the VirtualMachineImpl constructor - ClassPrepareRequest and ClassUnloadRequest. As a response to them a huge traffic is being sent from the debuggee.

Is it possible to transfer just those ClassPrepareEvents for which explicit ClassPrepareRequest was submitted?
This traffic is not only a problem for J2ME debugging, but also for remote debugging on a slow connection. See e.g. https://netbeans.org/bugzilla/show_bug.cgi?id=188732