Yes, it's about maximizing the switching speed by dumping lots of current into the gate, so that the power MOSFET spends the least amount of time possible in the transition state, and therefore wastes less energy and doesn't get as hot.
It says as much in the datasheets of the parts you listed :)
The ICL7667 is a dual monolithic
high-speed driver designed to convert
TTL level signals into high current
outputs ... Its high speed and current
output enable it to drive large
capacitive loads with high slew rates
and low propagation delays ... The
ICL7667’s high current outputs
minimize power losses in the power
MOSFETs by rapidly charging and
discharging the gate capacitance.