According to AnandTech, either wireless or wired charging from 0% to 100% should take around 3 hours well powered up and sleeping normally... Note that the last 2 percent will take significantly longer than you would expect. If you are getting sub-2 hour charge times, you are fine. Turning off the phone will also cut your charge time significantly.
If it really bothers you, and you battery is pushing 18 months old or more, replace it... it is a simple procedure that takes about 30 minutes even for the less than technically inclined, and the tools and battery needed costs less than $30, the battery is $12-$15 by itself if you have the tools that is all it will cost.
I frequently drain my phone to around 25% and connect the charger, in about an hour it is in the 80% range, and 30-45 minutes for the final 20%. Lithium Polymer batteries do not charge in a linear fashion.
And if you haven't done it for a while, you should completely discharge your battery (until it hits 0% and turns itself off), and fully charge it a couple cycles... Many people might disagree with me, but that seems to help bring back the a little if you do it about once every 6-9 months or so.