The free version allows a 4gb drive to be created. Obviously you need the free system RAM. Other very inexpensive paid versions include more options and functionality.
I have been using it to handle my Chrome temp files and cache, but it seems to work well to build on as well. It can be used just like any other Windows folder and saves data to HD on shutdown.
I do not have any benchmarking, but if anyone does, please share.
As you probably know, RAMDisk is not just a windows thing and may be used in a variety of situations on various operating systems.
Someone should consider using a RAMDisk if it decreases the time it takes to complete the work and it does not introduce unacceptable risk. But of course that depends upon each particular situation.
Many people are not aware this option exists for current Windows, so I thought I would mention it. Many Linux users are aware, but I will provide a link for completeness.