Can you make the speed of light faster?

Neutrinos would be even better. Trouble is building a receiver that isn't a cubic kilometre of ice.

Skip fiber-optics and "tunneling" all together, and switch to a networking protocol based on exchanging neutrinos... They'll happily go straight through the earth at light-speed.

And there are plausible alternatives to reducing the latency of the physical links... You could have a lot more smarts in the routers at both ends of the links, understanding TCP/IP, and proxying numerous protocol details, rather than mindlessly transferring unnecessary packets.

For example, if the router at the server ends store entires segments of a TCP exchange (part of a file download) in their buffer, the nearby router could send back a forged ACK (with minimal latency) to continue the processes. While that's happening, it's transferring the entire exchange to the router nearest the client PC, which then masquerades as the server, sending these packets, handling ACKs/NACKs, retransmits, and other details. The routers (acting as proxies) could also get more aggressive, like toying with different MTUs on the source and destination, or cranking up the TCP sliding window. The two routers might even benefit from transparently compressing some of the data at the source, and uncompressing it at the destination.

I'm fairly certain that the main cause of latency in these sorts of cases is not the speed of light. It's due to the large number of devices that these frames and packets have to traverse on these extremely long paths. If you laid dark fiber between NYC and Sydney and *only* had repeaters and amplifiers I doubt you'd experience enough latency to cause one to consider changing the laws of physics. But it's very expensive to do this so most traffic ends up traversing numerous networks and devices--each adding a little more latency. So I'm rather doubtful that speeding up the light a little is going to make much of a difference on its own.