1. If your applications use features which were well optimized in 4.1 you might see performance degredation (wtf?).
2. As of now 4.1 will only get critical bug fixes.
3. Amazingly it appears that 5.0 is slightly slower than 4.1. Why this is I don’t know.

I’m leaving this one to go to the dispearsed storage engine tutorial as I’m bored to death with this. Nothing interesting.