Fun fact: for the Test Size vs Latency plots, if you multiply the Latency y-axis with the x-value you'll get a plot that is close to piecewise linear.
You'll see what I mean if you paste the following two expressions into https://www.desmos.com/calculator and compare their plots:
y=\left[1...4\right]x-\left[0...3\right]^{2}
yx=\left[1...4\right]x-\left[0...3\right]^{2}
9
2