Check your "Throttle Event Limit" setting. It defaults to 0, but you can try setting it higher. It's in seconds, and controls how frequently events are handled. With a setting of 0, it handles everything, but setting it to 0.5 would make it ignore extra events that happen more quickly than half a second.
If that helps, and you're curious, you can set Log Throttled Events to see what's causing the problem.
If that doesn't help, some people have had success with disabling the Extra bar.