The speed of recharge done using Oxigen is very fast and if you are using wallet then it will obviously be much faster as you need not to go through the payment gateway while you are recharging.
What all you need is to add money to the Oxigen Wallet and proceed the payment using the wallet while recharging. Recharging through wallet saves your time and gives you "no-hassle recharge" experience.
I have used many wallet e.g; Paytm wallet, Mobikwik wallet, Oxygen wallet an many more. And I found the Oxigen wallet pretty good.Happy Recharging