That ignores a lot of things, like why it has to load so much information off the disk to boot. The entirety of Windows 95, the interface of which is not much less computationally intensive than modern Windows, fit in <50MB. Loading that from disk today, even with spinning rust, should be nigh-instantaneous. What justifies orders of magnitude more data loading?
Because each core is 4 orders of magnitude faster and it has multiple cores?