1: One of the major problems with BSNL Dataone Broadband connection is the DNS servers they provide by default. Most of the time they are very slow and sometimes they fail to respond. Open up the network connection profile and edit TCP/IP settings. In the DNS server address fields, specify the following DNS server addresses: 22.214.171.124 and 126.96.36.199
Disconnect the connection and then connect again. You are done.
This specifies third party DNS servers which are significantly faster than BSNL Dataone's DNS servers.
2: Firefox users can use FlashBlock extension to prevent downloading of Flash content by default, thereby significantly speeding up browsing experience. This is more of a passive tip in that reduces data usage to improve your overall experience.
3: You can try to increase your broadband bandwidth tweaking the TCP/IP parameters. The process is simplified by using TCPOptimizer, a free tool.
It helped me, your mileage may vary.