Although we were permitting the io thread to maintain events in a sorted queue, compute threads weren't having much luck acquiring the lock needed to insert events into it.  The result was that events would be added to the queue in batches, so ordering was far from optimal.
Now, we reduce the priority of the io thread to ensure compute threads get priority when they try to insert an event.
Additionally, increase the length of sleeps from 100ms to 5sec, since 100ms is ridiculously short.
Finally, force the io thread to pause for a minute at the beginning, to give the computation threads a chance of building up the start of a queue.
Add useful watches for understanding the impact of the new io thread.
Allow the io thread to accumulate as many as 5000 events in its queue.  Not all of those events will have vectors associated with them.  We'll see if that uses too much memory...
Since we're now running the io thread with low priority, maybe it makes sense to run a compute thread on every CPU again.  Incrementing the number of compute threads requested by one.
Too many times code has crashed without a useful backtrace.  Making compilation "debugged" by default.