Do not use beam lasers, especially not as the main DPS source. Extremly inefficient, even with efficient it's meh even though forums will try to convince you otherwise.
Efficient isn't the best way either. It looks great when you can fire indefinitely due to low capacitor draw. But lasers have INSANE damage penalties even at medium range. Unless all your fights happen at point-blank range, efficient is not the best mod.
Use long range. It completly removes the damage penalty. It's a massive total damage boost and gives you ridiculous flexibility.
A full laser build doesn't work though, lasers use too much distributor draw. On the FDL, a huge+med+med fixed long range pulses are ideal, put whatever you like in the empty two hardpoints (railguns with superpen and feedback are good, high yield fixed cannons are good, missiles are fine, corrosive MC is good).
While I may not alter my current FDL build to follow your advice, I am going to test it out on my Anaconda and Corvette. I knew the long range mod increased your maximum range, but I did NOT know that it also increased the damage drop off to your maximum range. So this is definitely worth some testing.
+1 Rep for showing me something new.