I have read a lot that PHP 7 out performs the previous versions of PHP. I am thinking of moving all my websites to PHP 7 so that my sites enjoy a better loading speeds. Please tell me any hosting providers that let me switch my servers to PHP 7
You will need to contact candidate host sites directly to see if they support it, or if you can install it. Many today will use either virtual machines for their hosted customers, or containers such as Docker in order to give you a safe environment that will not be interfered with by other users and vice versa. If so, then you should be able to to install PHP 7.x in your hosted environment, or they can.
Although there are many hosting providers which are providing php 7 hosting. I will recommend you to choose Cloud servers such as Digital Ocean and Vultr. If you are not a much technical person then it would be a better option to go for managed hosting platform such as Cloudways. Cloudway is providing php 7 hosting as well. You may deploy php 7 on new server as well.