Just a rather basic idea, based on my recent gameplay. As your fleet gets bigger and bigger, and heavier ships join in, your overworld speed slows down considerably. So much so, that even trying to catch a fleet traveling the same speed as you is a question of dumb luck (i.e. they happen to be running right towards you and you manage to 'tag' them before they can turn away). So I was wondering if one of the following two features might be considered:
1.) "Fleet Travel Speed" character skill: Fitting with Starfarer's almost Mount-and-Blade feel, this would probably be the more likely of the options. Sacrifice some of your hard-earned skillpoints to give your fleet the edge on the overworld map.
2.) "Sprint" feature while in overworld: This is what I had in mind before I remembered the RP features still to be added, but... The fast-forwarding on the map gave me this idea. What if you could make your fleet 'sprint' (let's say 150% speed bonus) for momentary bursts? This would allow you to close the gap on an enemy fleet that is JUST out of reach. The downside would be excessive fuel and supply consumption (Double? Triple? What's a reasonable amount?) and maaaaybe, to discourage having tankers loaded up for the sole purpose of sprinting around, maybe damaging the hulls of the fleet's ships a bit?