Ok I will try.
And what about this? (which is the main issue):
If I create a new page/post with w3 Total Cache activated, theme's color returns back to default and visual composer doesn't work perfectly. This happens only during editing in frontend. When I open the saved page all colors are my custom.
Here the screenshots of this test page
https://www.pianosegreto.com/visual-composer-issue/:
1) During editing with Visual composer and W3 total cache activated
http://prnt.sc/eablf8
2) When I open the page normally after page save:
http://prnt.sc/eabm4k
It is impossible to work in this way. I have always to disable cache plugin and site becomes too slow for users that started to complain.
Thank you for your help.