High server load leads to server and database fail

Hello,

I have a big website that is ranked 30,000 in Alexa. I had to move it to a dedicated server for better service. However, ever since I moved to this server the WordPress is having a problem with the server load! It increases the server load once I launch the website I get warnings of high load and use of the memory and it takes hours till the server and the database fail and try to restart itself and fail again. Apparently, there is something going on at the background that consume the server power. It is not a specific plugin as I tried to inactivate all of them and activate them one by one but still cant know which one as It gets busier with every plugin I activate. Even without plugins it has a high load. I excluded the visitors high load as the website has been offline for a week so the visitors aren’t that much when I try to launch the WordPress.

I need professional help and I’m willing to pay for troubleshooting and fixing the problem.

Please help…Thank You!