While the Y-axis shows 0.5 seconds resolution, the data is truncated to seconds. The test in builds 33 & 34 have run for 1.8 and 1.9 seconds, but both are displayed on the graph as 1.0s.
I don't see why there should be any truncation / conversion to integers. Isn't it possible & simpler to just use the floating point data from the report in the graph? I assume here the truncation to integers is non intentional and just an oversight, but maybe there is a good reason for the truncation... ? I think (but not 100% sure) that there was floating point data in the previous style of duration graphs.
Having the actual floating point values plotted would allow to properly see performance improvements of our core algorithms in these graphs. These performance improvements are typically in the range of 10% - 20% and are now invisible due to the truncation to seconds.