How much disk IO does this program generate? Why?
In any case, the OS should cache stuff and give similar performance to using a ramdisk, provided you have enough spare ram.
When I worked at Microsoft back in the 90's I inquired around building 26 as to why I couldn't create a ram disk on what was to become Windows 2000, and this was basically the answer. So yes, if caching doesn't solve this then caching hasn't been implemented correctly.
Remove the fsync or use libeatmydata.
> So if I'm writing GB of temp files
The kind that won't fit on a ramdisk in the first place? And this particular use case shouldn't need that.
If your temp files fit in ram along with running programs, then they should stay cached. A ramdisk should only be needed in edge cases where you want to manually force other things out of memory, or because you particularly want to avoid extra writes to disk. In general performance is supposed to be boosted just as much by caching.