Opera Unite Web Server Benchmarked
worb writes "Opera Unite comes with a web server which is supposedly going to 'redefine the web.' But how well does it actually perform? Is it a threat to other server solutions? Someone put it to the test, and published the results. While nginx, one of the fastest web servers available, is 5 times faster, a PHP+Apache+MySQL server is only 2 times as fast. A compiled C++ server, the MadFish WebToolkit, is 6 times faster. He concludes that Opera Unite's server is impressive, and that the others come nowhere close to the ease of use."
This is an Alpha or Beta. Opera 9.64 (final) is only 5.3MB large.
On my computer Firefox consumes way more memory than Opera - but it has so many extensions and plugins installed, that I'd be surprised if it didn't.
all of your exchanges pass through Opera's servers first.
Only if you're behind NAT, and your router isn't configured to allow UPnP.
Otherwise, individual connections are truly peer-to-peer. Opera servers don't get involved. They are only used to publish the list of services available for your account, not to access them (except for the NAT workaround).