After Ubuntu published the latest Kernel Patches for Meltdown and Spectre the Kernel 4.4.0-104/109-generic let Intel Graphics freeze or hang on Compiz with Unity.
Install the latest Kernel 4.4.0-112-generic
sudo apt-get install linux-image-4.4.0-112-generic
sudo apt-get install linux-image-extra-4.4.0-112-generic
sudo apt-get autoremove --purge -y
This removes older kernels and save Space! Do test the PC for hanging again!!!
Thru current IT News you may have heard about the major Security Problem of x86 Technology.
If your Websites current hosted on VM at VM Providers, contact them to get current news about their bug handling of their VM Host Servers. If you get no details, then shutdown your sites temporarily, or look for a other solution which isn’t running on x86 Technology.
Otherwise you can try to switch from php-kits to static HTML Websites. On the Net there are very helpful tools to do this easy. For WordPress is a WP to HTML Plugin available. This dumps your blog to HTML static paket where you can use a raspberry Pi with ligttpd as litte Webserver instance up to the time the x86 Manufacter fixes the nasty problems. Remark Debian runs on other CPUs like Sparc64 Mips too..