Why circuit switching is not used for internet connection?

Because

• circuit switching is wasteful because the dedicated circuits are idle during silent periods. Eg; when one person in a telephone call stops talking, the idle network resources cannot be used by other ongoing connections.
• establishing end-to-end circuits and reserving end-to-end bandwidth is complicated … and requires complex signalling software to coordinate the operations of the switches along the end-to-end path.

Example: how long it takes to send a file of 64000 bits from host A to host B over circuit-switched network.
Suppose all links uses TDM with 24 slots
bit rate=1.536Mbps
time taken= 500ms
then, transfer rate= 1.536Mbps/24
=64Kbps
Therefore, it takes 640000b/64Kbps = 10 seconds to transmit the file.
Also we add circuit establishment time of 0.5 sec. So it requires 10.5 sec to send the file.
The trend is now in the direction of packet switching. Even many of today’s circuit-switched telephone networks are slowly migrating towards packet switching.