Units with a long load time have a timer shown below them.
Because a lot of units are very stupid and won't attack the target you want them to you can use this to micro units without having them waste 1600 damage shots on t1 engies.
It would be very nice if there was an ingame option to choose which units would have those bars because it will be very helpfull to have that for a lot of units (t1 bomber, t2 bomber, strat, percy, sniper boats, neptune, aeon destro, non uef battleships, etc).
Edit:
Might as well add some more things i'd like to see added.
- In the interface options there's an option called "Force Render Enemy Lifebars" which can only be turned on or off. The main reason for this function is so that you can specifically target weaker damaged units but that's why in other strategy games there is usually an option like "show damaged units only". To make it even better (but more work kappa) a slider could be added (1 to 100) to set the % amount of hp left on units before you want to let the lifebar be visible.