computer A in Japan computer B in Sydney
Is there a way to establish a secure tunnel between these two computer so that Sydney based computer B visit Japanese website faster and Japan based computer A can visit Australian website faster ?
Any open source solution to adapt ?
The main issue here is network latency; a signal needs some time to travel between Japan and Australia, and there is nothing you can do about that.
The other issue is bandwidth; but that is something a tunnel doesn't change either. The encrypted signal may compress better or worse, but overall, there shouldn't be much of a difference. You do want to use decent enough hardware on both ends though, so that the effort of encrypting and decrypting does not introduce extra delays.
The only thing you can do is run a caching proxy on either end, so that when you re-request a Japanese site from Sydney, the Sydney proxy will already have it and save you the trip to Japan (and vv.). If you control the websites on either end, you may also want to consider mirroring them; that way, there would be a copy of the Japanese site in Australia, and a copy of the Australian site in Japan, and both would be fast to access from their respective country.