[lincpimp]

Better driving usually helps me get around a track faster... Lowering gearing will help runtimes, although the power will still be there. More precise throttle control will help the lap times, so it sounds like you need a bunch of practice. Not that I can talk, I need practice too!

A smaller motor will produce less torque, but will be pricey.

Not sure if going down to 4s will do much, the motor will spin slower, and required higher gearing (more load) to do the same speed. So the pack capacity will have to go up for the 4s pack. Then it will weigh the same as the 5s pack. The 5s setup should be more effecient, so runtime will not necessarily be better.

A smaller motor with similar kv to your current motor, and lower gearing will produce less torque, lower top speed and increase runtimes. That is about the only way I can see to meet all of your goals.