Impact of android version on phone performance
It depends from which version you are going to upgrade. For example, if you are going to update to 4.4.x then yes, you should do it.
Version 4.4.x is a big leap on any Device.

See Kitkat 4.4.x release notes.

Other versions don't always have a positive impact on performance, for example, the performance of Samsung's version of 4.3 was worse than their version of 4.2.2.

Hope it Helps.