Just my two cents...

On the Indian Railways site, you can search for trains between certain important stations here. Once you specify the locations between which you want to travel and click the Get It button, you are presented with a search results page. You can select a train and get its seat availability, fare and schedule for the selected dates between the two stations.

When I tried it, I found something. Everytime you click on the Get Availability button, you are presented a message box that says,

Please note:
"PNR status" and "Accommodation availability" queries are very network
resource intensive queries. You are therefore requested to please wait for
sometime and not to re-submit the same.
Thanks for your co-operation.

Also notice that the three buttons on the top and bottom of the search results have their captions changed to Wait For Availability!

OK, guys, I get it. You want to prevent people from clicking the button repeatedly out of impatience. But for that, you can better disable the button, right?

The remaining two buttons (Get Fare/Get Schedule) also have this scenario - captions changing to inform the user to sit quiet. Disabling the button would be a better solution.