When your webpage is loading, it can sometimes occur that the original page displays for a split second instead of the variation. This twinkling is called flicker effect or flickering.
Why this flickering?
Consequently, if Kameleoon script loads after the webpage, the variations will also load last, creating this flickering.
How to avoid it?
Kameleoon's engine is maximized to limit the flicker effect. Therefore, you are unlikely to encounter this inconvenience during your A/B tests.
<head> element to make sure Kameleoon loads first.
For further information about where to put this code, you can read this paragrapher about the Optimum location for the script.