My players generally love rolling dice but this means far too many of them, not to mention a huge amount of attack throws by NPCs.
Classic Traveller Book 5: High Guard solves much of this, but serves for large-scale naval battles between multi-kton battleships better than for small-ship scuffles as envisioned by Classic Traveller Book 2.
Therefore, I propose the following streamlined rules. Their main purpose is to make combat a little bit more abstract and thus facilitate games in which the PCs are bridge crew of a medium to large (in small-ship universe, that is) starship. I recommend using the core CT Book 2 rules when refereeing battles between a few lightly armed small ships, such as a Free Trader ambushed by one or two pirate ships.
Turrets and Batteries
Each turret makes one attack, regardless of the number of weapons it carries. All weapons in one turret, with the exception of the lone turret of a 100-ton ship, should be of the same type. Two weapons attack in one roll with DM+2; three, with DM+4. damage is as usual for a single weapon. This reduces the rolls by a factor of 3 right out of the box. (this is inspired by a house rule posted by tbeard199 on CotI).
Ships with 4 or more turrets may have batteries of 4 turrets each. Any remainder of turrets attack individually. Each battery has one weapon type and all turrets should be identical. Attack is with DMs as above for multiple weapons per turret. Make a single attack per battery using the battery commander's Gunnery skill. However, damage "explodes" - for every 2 points (rounded up) the throw exceeds 8, the battery makes an additional hit. For example, Effect 1 makes two hits, and Effect 5 makes 4 hits (this is inspired by the Striker automatic fire rules). A single battery can generate up to 4 hits.
For example, a 1000-ton Light Cruiser has 10 triple laser turrets. It makes 4 attack throws per round: one for each battery, and one for each non-battery turrets. This is instead the 30 throws it would have made under the baseline rules.
Weapons do damage as usual - for example, three hits from a pulse laser battery will mean 8 rolls on the damage table.
Fighter Mass Combat
Fighters operate in flights of up to 3 fighters. Two fighters make one attack throw together at DM+2; three, at DM+4.
Use the flight leader's Piloting skill as a -DM to hit the flight. Furthermore, fighters at 3G to 5G acceleration are at a further DM-1 to hit and at 6G, DM-2. Apply software DMs as usual. Any hit on a flight "mission-kills" one fighter.
After the battle, resolve the actual damage for mission-killed fighters - in many cases, the pilot survives, and/or the fighter is salvageable. Throw 2D, DM +the flight leader's Pilot skill. On a roll of 6-, the fighter is destroyed; 7-9; cockpit hit - throw 6+ to safely eject and avoid death; 10-11, fighter heavily damaged but salvageable; 12+, fighter knocked out but easily repairable.
Four flights are a squadron which attacks like a battery.
For streamlined combat, missiles move either in salvos of 3 missiles each, or in barrages of 12 missiles. Anti-missile fire targets the entire salvo or barrage. For each two points a single laser turret's anti-missile attach throw exceeds 8, remove one missile, up to a number equal to the turret's lasers (e.g. 3 for a triple turret). Batteries destroy one missile per single point the throw exceeds 8.
Any remaining missile hitting the target causes 1D hits as usual.