> time it takes to scan an disk

Do you mean loading all files from all your hard drives installed in your computer?
1st i would try "l" then "*"

for me,

pentium 4, xp, desktop, Fat 32, ztree can load about 3000 ~ 4000 files in 1 sec rate.

core i5, win 10, notebook, it is kind of untestable, it pauses and stops loading
sporadically then continues to load. it is slower than than xp and pen4.
probably bacause notebook's hard drive's spindles are many times lesser, they can not keep up with the cpu. when i am copying in notebook, all multitaskings basically cease to work.

core i3, win 8, Dell desktop, dell told me OS is built with a motherboard, in an attempt to delete windows_old directory, i partitioned the hard drive. they lied to me.
it has not been fixed yet.
the loading file speed was about the same as xp in pen4 in my memory, maybe slower, since NTFS.

isn't ztree the festest file loader? i think so.