I'm a little confused over the performance of both. I have this
servlet to generate stock charts which runs on Sun 5.9. The original servlet was written using Vectors, there were a lot of them created, updated, and removed. The CPU usage (according to top) was around 3.50% all the time. Then I've converted Vectors to ArrayLists because there's no need for synchronization. I expected to have CPU go down, but instead it jumped to 7%. Then I found another two Vectors, converted them to ArrayList and CPU reduced itself to 5%. Although I have to mention that servlets now respond somewhat faster.
Can someone point out the reason behind all this?