Alternatively: It could be that Windows 10 has various performance optimisations that Windows 7 does not, and these have had to be undone as part of the fix. I

Alternatively: It could be that Windows 10 has various performance optimisations that Windows 7 does not, and these have had to be undone as part of the fix. In other words: If the fix would cause Windows 7 to lose X% performance, Windows 10 would lose that same X% plus any Y% advantage it had over Windows 7. (This is just a guess, of course.)