I am referring to testing in the editor. One disables triggers and then tests the map until the freezing stops. If freezing has stopped then that means that one of the triggers which were disabled is the cause. One can then try to isolate and recreate the freeze using similar trigger code until a demonstration map can be produced. This can then be sent to Blizzard for fixing in a future patch and based on this knowledge temporary/hacky mitigations can be applied.
The way to disable triggers is in a binary search style way. Start with large chunks of them until the freezing stops. Then out of that last disabled chunk work down the number disabled until they reoccur. Eventually doing this one should track down the freezing trigger. This can then be isolated and analysed as to why it is causing a freeze.
Unless user input is required, one can run these tests in parallel using LAN games as I described above.