I would also like capital ships to force fast ships to slow down. This way the fast ship would be forced to spend more time strafing, enjoying the scenery, and be in range of point defenses!When flying closer to large ships, your ship (or the drone you are remote controlling), will gradually be drawn into the influence of that ship.
The model of this influence could be in the form of friction from a fluid that moves with the capital ship. It tends to move the surrounding ships with it and also slows them down in relation to the capital ship.
And I imagine two ways of putting it in the game universe:
The first one involves having a capital ship equipment module, say "EM field generator", that creates this drag that diminishes with distance. You could upgrade both the distance and drag generated.
The second one, involves having big, globe-like perimeter shields, some hundred meters larger than the capital ship itself. Any ship closing in below a set speed could cross it without crashing into it. And once inside, it would be under the influence of this atmosphere, that would vanish if the shields are depleted. Of course, the fighters would be able to attack the capital ship bypassing perimeter shields!
What do you think?