Hi, I am dealing exactly with the same issue. Same laptop : Lenovo w250, Windows7 64 bits, 16Gb ram, corei7 processors, Solid state disk (SSD), etc.
I am using Vbox 4.1.6 r74713 and using a pre-built Oracle image with WLS, SOA, BPM, etc.
If I run it on my Dell Precision M6500, similar characteristics except for the SSD - just got a normal HD (so performance should be poorer), it runs way faster which is no sense.
Startup of WLS, SOA, BPM, etc takes 10 minutes in my Dell whereas in my Lenovo it takes more than 40 minutes!
Any tip, advice, experience would be very much appreciated. I have tried all things described in this thread before.