Having a slower computer is more likely to be a disadvantage for the other player, the same as your connection speed.

Their game will predict (to a certain extent) what your game is doing (ie. where you're flying) based on it's last communications.
If this information is not forthcoming, it makes an assumption on your location when you may actually be some way away on your own system.

This form of lag accounts for a huge number of "cheat" calls online as it can also affect guns and damage when connection is suddenly re-established and inflicts 'retro-spective' damage from someone who appears to be thousands of miles away. Having said that, there are cheating devices which can cause this as well.

Best way to avoid cheats:- Fly with players you respect and don't need to cheat. If you suspect someone of cheating, don't make a big deal of it (they're the ultimate losers), just don't fly with them again.