change the servo speed in the robot_go_straight function.
23/.992*(milliseconds) = delay cycles
for a servo 1.5 milliseconds is centered (or stand still on a modified servo). 2.0 is max, 1.0 is min. so since your servos are mounted and one is flipped you have to put one at full max and one at full min.
I believe the numbers right now are 25 and 44.
you can make your robot go a little faster by changing them to the max and min
23/.992*(2.0) = 46
23/.992*(1.0) = 24
so change 25 to 24 and 44 to 46