Knowledgeable Javascript Coder - Please Explain Timing Issue

I am using javascript to render some charts using the chart.js library. Everything is set up correctly and the charts are drawing correctly. The issue I have is about the timing issue difference between the two methods I use to get the data into the JS…

Both methods are utilizing a bubble RG with group by feature. There is no issue with timing of the data from the RG as it is loaded before the JS is run.

The two different setups are that in one method I use the list : join with feature.

Screen Shot 2020-07-11 at 12.49.07 PM

The other method I enter each set of data using ‘item #s

The reason for doing both methods is that I noticed when I switched from ‘item #s’ to the ‘list join with’ method my charts were taking longer to draw, and in some cases is was as much as 10 seconds. So I decided to do a speed test to compare the two methods.

What I found is very troublesome and I am lost as to why this occurs.

Attached is a gif of a video demonstrating the speed test

WHY TIME DIFFERENCE (1)

What I am doing here is running the two different charts at different times ( ie: 'item #s first, then ‘list join with’ second and vice versa )

The time differences is alarming and causes me to believe there is either an issue with JS computing the ‘item #s values’ or a bug with bubble (tend to lean towards the latter)…however, with my limited experience I really don’t know if there is something else going on that an experienced Javascript coder could explain.

In the gif when I run the ‘item #s’ first, those charts take considerably longer than if I ran them after the ‘join with’ chart. When I run the ‘item #s’ first with all dynamic data loaded it took about 22.5 seconds to draw the chart, while the “list join with” chart takes just over 3 seconds to draw.

If it was always this way I could just chalk it up to ‘list join with’ is faster and move on. However, that is not the case.

When I run “list join with” first, the time it takes to draw is similar to when it is ran second. It takes the 'list join with" about 3.5 seconds to draw when I run it first. Then, when I run the “item #s” after the chart draws in less than 1 second — about 750 MS.

So what gives? Why is it that if I draw the ‘item #s’ chart after the ‘list join with’ that the ‘item #s’ chart draws about 21 seconds faster?

Is there any plausible explanation for this, or is this some kind of bug? I lean toward the bug issue because on my first test with this I was getting error reports and bug reports in the debugger from bubble when running the “item #s” charts first.

Here is video to watch more easily than the gif