You asked a question and someone offered a suggestion you were not looking in the right place. Then you become incredulous at their suggestion and start asking a whole bunch of sarcastic questions implying relevancy.
How about you google you problem and figure it out? No one will help you with that attitude.
Do it. I waited for release but it was smooth as butter before. It has some edge case issues but on the whole it’s been better than staying on plasma 5.
You can restrict the size of the ramdisk so you do not end up killing processes. A large amount of ram is not mandatory.
tmpfs is the filesystem you are looking for. You can mount it like any other filesystem in /etc/fstab.
tmpfs /path/to/transcode/dir tmpfs defaults 0 0
I transcode to ramdisk.
OpenGL is the only other open source alternative. Vulkan is developed by the folks who created and manage the OpenGL specification. (https://www.khronos.org/) To shorten the list of differences I will specify one. OpenGL is ancient and can not compete on modern hardware. Vulkan is the new hotness that everyone in the future will support.
There are a many reasons that more fully answer your question but this is the short/fast.