Hi Frank,
I only use this software to plot the CSV files:
amund7/UDPLogger (Windows installer under 'releases' to the right)
Otherwise not sure what you are looking at, are you plotting the Speed signal? To get the best accuracy, use the Speed tab and record from there, you can even clean it up by deleting all the other signals, or creating a new tab with just speed. This is more important the slower your adapter is. A regular ELM327 can get 50-80 packets per second, and by showing only the Speed signal you should get those. An obdlink can take up to 1000 packets per second, but even that is far from enough if you are trying to record the All tab. Also temporarily disable Teslalogger if you use that, it also holds open for all the packets it sends, slowing down your Speed signal.