Drag and drop of files between folders in Project window is too slow

When I drag a C# into another folder, I leave the office and come back the other day for the operation to complete, only to see that I have somehow selected the wrong folder (when I intended to select a file) and I have to clean it up.

Why is this so slow? I rather just go through the windows file explorer and rearrange files there because Unity’s project view is too slow and doesn’t give me feedback on what I am doing.

Sounds like something specific to your computer. For me, the file move is almost instantaneous followed by the normal recompile the same as if I had just modified a script (2018.2.9, Win10, Intel i7 6 core, 16GB ram, SSD).