Kolto Injection (KI) costs 25 energy.

At 5 Energy regen per sec it takes 5 seconds to accumulate the energy to cast KI.

At 4 Energy regen per sec it takes 6.25 seconds to accumulate the energy to cast KI.

At 3 Energy regen per sec it takes 8.33 seconds to accumulate the energy to cast KI.

At 2.5 Energy regen per sec it takes 10 seconds to accumulate the energy to cast KI.

At 2 Energy regen per sec it takes 12.5 seconds to accumulate the energy to cast KI.

Dark Infusion (DI) costs 55 force. (Before the talents to decrease it's cost).

At 8 Force regen per sec it takes 6.875 seconds to accumulate the force to cast DI.

At 8 Force regen per sec it takes 6.875 seconds to accumulate the force to cast DI.

At 8 Force regen per sec it takes 6.875 seconds to accumulate the force to cast DI.

At 8 Force regen per sec it takes 6.875 seconds to accumulate the force to cast DI.

At 8 Force regen per sec it takes 6.875 seconds to accumulate the force to cast DI.

Apples are not oranges. Also, you're ignoring Stim Boost.