lengo123

Hi vmdials.

I removed some code related to google analytics (google tag manager), which it was displayed at the header.
After that, everything are fine as before.
If you have still problem after that, you should check any catching plugin and of course update your theme.

Good luck!

Finally i resolved the problem. It was the header that caused the problem. I changed the code inside the header and the white flash disappeared. Thank you for your support anyway!

Thank you for your response.
I deactivated all plugins, as you recommended, but the problem is still there.
Any other idea?