ha, only in sfc3 could you pull a trick like this. I never did like the speed based on mass thing, really kind of skews things. I was wondering when someone would figure out you could just dump most stuff and fly at speed 100. then a standard ship with a standard load out kind of sits there going "hmmm.... what to do".
I would imagine that your super speed opponent has an advantage if he chooses a race that has fast recharging weapons that go long range.
In SFC2, having no shields was like suicide. People who forgot to hit the red alert button to raise shields were dead in a few seconds. No one tries to fight without shields, cuz you coudln't go faster than your opponent and charge suitable weaponry at the same time, the only option is to retreat.
Your best bet is to forgo using heavy weapons that don't have range. Just stick to your longest range weapon, crank the speed, and go. Overload your phasers or disruptors and keep plinking away, keeping in mind that in a clash, you have advantage. Make sure your heavies are saved for when they're coming in on you, and then lay it thick, H&R his warp core and stuff, just target his hull and rip it to shreds, and keep closing. Having no shields may mean hyper speed, but it also means that they have to play a mean game of keep away.