I have just received my new 5520 and have pensioned my old precision M4800.
The new one with Windows 10, SSD takes longer time to boot than the old one with Windows 7 and a SCSI harddrive. I have compared the time it takes from pressing the start button until the Win logon screen is available. The amount software on the 2 machines is 100% comparable.
The Win10 boots faster and a SSD is so much faster than a SCSI drive - can anyone explain to me why the 5520 is slower?