Yeah, PHP is extremely fast. In most cases, slowdowns are casued by Apache, or wrongly designed database with a lots of different queries. But even your slow hard drives can cause disk overload, which makes your database performance slow. Use RAID 10 with HDDs, and RAID 5 for SSDs. I prefer samsung 840 pro series, they are really undestroyable

I suggest you to never use cPanel or so. You should install and configure your server manually. It worth the extra time, cPanel causes much overhead to your server.
I have a debian server, with well optimized nginx, PHP and MySQL. It serves tens of millions of requests daily. I could even use memcached to improve performance.
It is just a Xeon E3 with 32GB DDR3 and SSD disks.
Also, do not believe people who say you need X*Gbit bandwidth for a blog, or forum. You only need that huge bandwidth if you offer big file downloads or streaming video.