What is your ship’s “Warp Core”?
The STO ship’s Warp Core is basically your ship’s power core that provides power and energy to your ships systems. It acts as a equivalent to MP / Mana / Magic Power in conventional mmorpg and rpgs in Star Trek Online. However unlike mana, the warp core power will not deplete, but instead players will have to wait in order to fire phasers. So by simply allocating more power to your beam weapons your phasers will be faster. The allocation of warp core power will not only be limited to weapons. Gamers will be able to allocate power to shields and propulsion as well and to take it even further, you can choose exactly which shield to give more or less power to.
Power diversion has its negative points too, in the sense that if you divert more power to one system, then another will have less power, therefore will become less effective consequently. So there is no such thing as setting all your systems to max power in Star Trek Online. Your Warp core power allocation is indeed a tactical decision that you will have to make in battle continuously. A typical scenerio in STO will be boosting your shields to engage enemy attacks and diverting power to weapons after the enemy attacks for the counterattack torpedo.