Weird artifact while decelerating high speed robot arm

Hi, I'm building a high speed rDelta robot arm.
I have a test program that just repeats a circle move twice at nearly 2m/s.
This works great except i noticed a weird deceleration artifact. It stops slowing down for a moment, speeds up and then decelerates into its last point.
This is also visible on the robot itself.
The blue line in the plot I attached is velocity from the hal pin motion.current-vel.


As I've been playing with accelerations and velocities in the .ini file I suspect something in there might be the cause. Any ideas?
I also attached my .ini file  

ps I'm building some custom plotting software but the same thing is visible in hal-scope

andypugh wrote:

Is there any chance that this corresponds to something in the kinematics? Maybe an inflection point in one of the joints?

Its possible that at that point another joint starts contributing to the motion.
Think of 2D motion on X & Y at 45 deg at max velocity. Both axes will be moving at their max, but the total combined axis velocity  will be about 40% higher.

I don't think so. The same point is being passed through twice in this graph. If it was an inflection point there would be multiple artifacts, right?