Well, its like this a spark plug's spark efficiency depends a lot on the cables.
example, if you have a good spark but the cables have high resistances do you think you can get better spark ?
Spark plug and cables work togehter as a team....Well simple, good plug cables like NGK, Ultra or Hotwires. They have lesser resistances in the cables which means that current flow is more smoother without much electrical resistance. A performance plugs is better then normal plugs cause the spark that it generates its better than normal plugs. So if you use performance plug with ori cables maybe the spark that produce by the plugs is not at it best efficiency....
theres a formula to calculate between voltage, current and resistance..
V=I*R
V-Voltage
I- Current (Amp)
R- Resistance
So if R is greater then V will be lesser.....A better spark provide beeter combustion and FC...A good set of cables wont affect your ICE system cause there will be no leaking of current that affect your ICE...