There are two parameters that are limiting your device speed:
max_trans_vel: 0.5 - this is the maximum linear speed in any direction (as a resultant)
max_vel_x: 0.7 - this is the maximum linear speed along x axis
Both parameters are in
m/s. Set speed will never excess these values.
You can also check the
/cmd_vel topic to see what speed is being set by the path planner.
You should also keep in mind, that path planner takes into account many factors while selecting speed, these could be distance to obstacles, trajectory curvature or distance to be traveled.