A feature to use system ram for working storage. Many have upwards of 64GB of system ram available. So having the app be able to use upwards of 45GB of it for working space wouldn’t be a huge issue while also saving lots of wear and tear on your SSD or the slow down of using a traditional spinning hard drive.
Besides, it’s not like you can safely just resume a download if it fails or freezes half way through, you have to restart the whole thing anyways.
So, can just reserve the system memory, use that to hold the working information, then release it afterwards with the only actual disk activity being saving the finished product.
Even if only those with 64GB+ of system memory can use it, that is still a lot of people and would both speed up the process and save the durability on their storage drives.