I recall UMSDOS being a performance nightmare. A 486DX2-80 paired with a much newer circa-1997 3GB IDE hard disc on a VL-Bus controller should have been CPU-bo

I recall UMSDOS being a performance nightmare. A 486DX2-80 paired with a much newer circa-1997 3GB IDE hard disc on a VL-Bus controller should have been CPU-bound. UMSDOS made it disk-bound. Its most solid use case was probably "mount a shared prtition and still have some Unix filename support".