Dear PenciDesign,

thanks for your reply.

I can't share admin login to the site, on other hand i could conduct an online meeting to give a remote access.

best regards,

Follow other site speed factors like site cache data if you didn't accomplish it yet!

As it described in the theme product page 

That your theme has high rating in the google site speed, unfortunately after we install it along with demo data, it show the opposite  which the bad ranking in speed where the site takes long time to be ready for visitor for interacts with the content! 

for mobile browsing the best ranking was 35 out of 100!

where the the time for interactive is 14 s, which is extremally high! 

while it was better in web browsing 57 out of 100!

screenshots are attached for reference ! 

best regards