In general higher cadences are less efficient than lower cadences at a given power output. in general, the literature shows the most efficient cadence to be closer to 60 revs/min, rather than 100 revs/min.
this efficiency is thermodynamic mechanical efficiency, and is basically, the effeiciency that allows you to produce a specific power for the lowest energy input. at higher cadences you have to expend more energy to turn your legs at that (higher) velocity.
however, it feels more comfortable, because in part peak forces are reduced at higher cadences. it's also easier to accelerate from a higher cadence than a lower one.
during cycling (except for e.g., a standing start sprint) the forces are very low to moderate pretty much whatever the cadence.
as the absolute power output increases, so does the most efficient cadence. Pros absolute power is way higher than your average rider, and their most efficient cadence will be higher.
under given conditions at a given velocity, power will be the same whatever the cadence. your ability to do e.g., dead lifts and weight training isn't related to endurance cycling performance as forces are very to low moderate (e.g., climbing an alpine pass during a mtn TT, by a top 5 rider on GC in an event such as the TdF, will likely require an average force on the pedals of ~ 250 Newtons -- which is equal to about 25 kg, between both legs).
In general your best and most optimal cadence will be self selected under the conditions that you're riding under. additionally, at some points you may have no control over your self selected cadence. for e.g., riding up a steep climb (e.g., 15%) may mean you are riding at your 'sustainable' power output limit (e.g., 350 W). that power under given conditions will produce a specific velocity (say 15 km/hr). at that velocity you may not have a gear low enough to pedal as the cadence you want. for e.g., if you're lowest gear is 39 x 23, that may mean you're only pedalling at 60 revs/min**. pedalling faster, will mean you'll have to ride at a faster velocity, which in turn will mean you'll have to produce more power. if you can't produce more power then you can pedal faster.
**i haven't checked what cadence and speed is associated with 39 x 23 at 60 revs/min. i just estimated it!! i.e., wanted to give you an idea of what happens.
ric
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