Vulcan Cannons do 500 DPS. Even after the 1/4 modifier vs shields and armor, that's 125 DPS for 20 FPS, which has to be the most flux-efficient weapon in the game. Its only downfall is the 250 range, but missiles and fighters like to get real close anyway. Vulcans are far more effective at protecting the targeted ship than any beam-based PD.
Beams that aren't Tactical Lasers are underpowered, and Tactical Lasers aren't particularly amazing either. Not dealing hard flux is crippling, even with their high range. Graviton Beams are kind of a joke, being only slightly more effective vs shields than 2 Tactical Lasers and less effective vs armor and hull. Their only good point is that they're flux efficient, but they do so little that their flux efficiency is wasted. They're only good on Close Support Wolves, and only then because the Wolf has bad flux stats, and CS Wolves are only really good against other Frigates anyway. I would honestly rather leave the weapon slot empty than use a Graviton Beam on anything other than a Wolf, they're wasted OP. High Intensity Lasers are even more of a joke; it's just 3 Tactical Lasers that can't turn as fast while firing. Tachyon Lances are terrible now that the EMP-Arc bug has been fixed. It's just a Phase Lance with more range and 50% higher DPS that costs 3 times as much OP. A good starting change would be to double or triple the damage of Graviton Beams, High Intensity Lasers, and Tachyon Lances, see how that effects the game, and work from there.
Phase Lances are half-decent. They're sort of like Harpoons, in that they're best used on ships that are about to overload, but they need to be supported by other weapons that deal hard flux damage. The issue is, they take up a medium slot and high-tech ships don't have the medium slots to spend on dedicated finisher weaponry. I'd suggest either making them a small weapon and reducing the refire rate from 10 to 6.5 shots a minute, making them a high OP small weapon with a specialized purpose sort of like the Antimatter Blaster and Light Needler, or leaving them a medium weapon and increasing their refire rate to 15 shots per minute, making them more able to bust through shields on their own.