If I were to guess at this problem without looking at your code, I would say it has something to do with how you're dealing with time. In particular, this sounds like a system that doesn't allow 'missed frames', and tries to catch up to where it wanted to be, so it keeps executing them until it's caught up.
After looking at it, I noticed that your Updater thing uses a Timer.scheduleAtFixedRate, which looks like it might have a
behavior similar to what I'm describing.
"If an execution is delayed for any reason (such as garbage collection or other background activity), two or more executions will occur in rapid succession to "catch up." In the long run, the frequency of execution will be exactly the reciprocal of the specified period (assuming the system clock underlying Object.wait(long) is accurate). As a consequence of the above, if the scheduled first time is in the past, then any "missed" executions will be scheduled for immediate "catch up" execution."
That sounds exactly like what's happening.