Sorry for the late update.
//Does *any other* hashing utility works with the same speed on the same system when in the "normal" windows install and when in the PE?//
I have created a physical image of a disk using FTK imager in WinFE and in normal windows environment . The result is same as my hashing utility ie. FTK imager takes more time to create the image of a disk in WinFE compared to normal windows environment in same system.
I had added driver packages(of Chipset,Serial ATA,Removable disk) for the specific system(Dell Laptop) to the PE - but It doesn't make any change.
I have found a driver cab for WinPE from Dell website(http://en.community....-5-0-driver-cab). I tried these drivers too but nothing solves the problem
In my hashing tool, there is a provision to view the speed of processing data and I noticed that this speed is maximum at begining(say 80 MB/S) and then it is slowly decreases and come to a constant value(say 50MB/S).
I tried to trace my hashing tool using Dependency Walker and with Procmon. But it seems all depended dll files and subsystem are available in PE also.