Couple of things to consider before upgrading your CPU. Depending on your motherboard model, you may not be able to do much with an unlocked CPU versus your current locked CPU. So, what model of Asus motherboard are you using?
Also, even with a new unlocked CPU, you won't get a massive increase in overall system performance just by swapping the CPU. You need to consider the relative costs of adding the new CPU vice the gains you achieve.
To measure the difference gained, just run a benchmark app before and then after the swap. Easy.