If you experience "lag" and display problems with gauges and buttons in the menu, you can change a variable in a text-file.
"rtMinRefreshInterval" is the variable, in number of milliseconds between screen redraw.
You find it in the installation directory under config/v3gui.cfg
Check the CPU usage of the VemsTune process, press shift+ctrl+esc and the process manager appears. If the usage is at 100% for the process when online to the ECU then you have issues. Edit and replace the number with a high enough number so that it flows well on your computer, setting it to 200 would be 5 Hz = 5 redraws/second. By mistake this is set too low in some releases.
It's not useful to have any faster redraw than the update rate you get from the ECU, which is usually 15-25 Hz.
This can help a lot on some old laptops that have really crappy ATI chipsets with poor 2D acceleration where the CPU has to do the dirty work, which is not nearly as efficient. Obviously if you get a high update rate from the ECU and have this variable set too low (short interval between redraws) then the computer won't keep up. At the moment the redraw is interrupted which can cause graphics glitches, the developers are working to fix that - if it wasn't for that I wouldn't tell you about the variable, so this problem is probably solved by the next release.