The "easy" fix for this, if you have spare Ethernet ports, is to put a dedicated switch between the machines. I'm using Synergy right now, with peripherals on my Windows game machine (where having them connected directly is beneficial), but driving a MacBook most of the time. I have a cheap 4-port gig switch between the machines so that Synergy doesn't have to go over WiFi. The machines both use WiFi for all their Internet traffic. The switch is also great for VNC and SSH between the machines. I don't think Airdrop has any real effect; WiFi just has higher latency, more variable latency, and more packet loss than a switch will have.