IRCTC Server Issues & Solutions

IRCTC is India's biggest ecommerce portal with hundreds of thousands of bookings made on daily basis. Now, operating a large website isn't a new technical challenge, yet IRCTC servers seem to have issues handling the payment transactions and overall traffic. The problems start right at the time of logging-in to the site and it usually takes a long time to just get past the user-login page. Then there are issues with session timeouts, multiple logins, incomplete logouts etc.

I'm curious to know about the technical challenges IRCTC faces and possible solutions it may implement. Is it the bandwidth issue or the overall load balancing issue - I don't know. If anyone knows the details, please feel free to share.

PS: I think it's TCS (Tata Consultancy Services) that manages and operates the IRCTC website. Can someone from TCS enlighten us on the issues?