Is it possible to have differend php version on different domains on the same server on hosting performance?
This basically is a topic that technically is up to you. If you are using the same OS for everything without LXC containers, KVM, or chroot jails, then you are quite limited. The Red Hat branch (RHEL, CentOS), however, offer you versions called “rh-php” which enables you to parallelly install both versions. However, only one server can be served through one port at a time, so if you want to have everything available through the same public port family (80/443), you may consider using a proxy (for Linux, there’s pound). It can catch per-domain and forward traffic to different individual ports you can then server through your different web server versions, and it is e.g. also SNI aware.