Billdesk.com is a Payment gateway which mostly use by Indian government sites for online Payments.
You can see this Payment gateway when you going to pay your electricity online payments other then BSNL I mean Indian government telephone site and all.
It means it is trust worthy site which Indian Government uses on their sites to allow Indians to pay securely online their payments.
I used this Payment Gateway on Government sites to pay my bills and it is not slow in-effect it is very easy and comfortable Payment gateway to pay payments online.
I always choose Billdesk if I see this is payment gateway.