Your 16GB is enough *if nothing else is running*. Other things are running and using up around 8GB themselves, which means there isn't a full 8GB free out of the 16GB for Corona and C4D to do their thing. You can see this in the "14.1GB of RAM used by all running applications" which is pretty much all your RAM, and this is why Corona and C4D can't find the 8GB it needs to work. This is why I mention close all other applications (no Photoshop, no browsers, etc.) as that may be enough to squeeze this particular scene into your current RAM.
If you run out of RAM, the render gets MUCH slower, because now Corona is having to read and write data to the hard disk because there is not enough RAM. Hard drives are hundreds of times slower than RAM, even SSDs are that much slower, so your render will slow by that amount.
Your CPU determines render speed, so long as you don't run out of RAM - if you run out of RAM, any CPU no matter how fast will be very slow :)