This suggestion is a little bit weird,as it requires understaning why I suggest it…
So,at first,when you locked-on a target,you were able to use targeted modules/abilities,homing missiles and see the target lead,wich implies that the ships CPU required some effort to lock on to the target,using some sort of energy to mark the target . Now,you need to lock on a target to use targeted modules and homing missiles,but you can see the lead on the target by simply moving the mouse cursor over the target,wich implies almost no effort from the CPU to lead he target(maybe simply visual targeting and simple calculations),while the first mentioned actions need some consistent effort wich requires some energy.
Now,my sugestion is that locking on a target should consume a small amount of energy,ship-size depending,wich in my opinion can make some interesting strange situations and bring a little bit more chalenges to the players,making them think even more about how they are wasting that energy bar.
Now,we should think wich should be better,an one-time activation enrgy cost,or an energy-per-second effect…
Of course,it won’t be a big amount,I think that around 25 energy on cast for Interceptors,50 for Fighters,100 for Frigates and 300 for Destroyers , or as an energy-per-second,it could be 2 energy/sec for Interceptors,4 energy/sec for Fighters,6 energy/sec for Frigates and 10 energy/sec for Destroyers.