Why is W10 so inefficient on some UI interactions?

With the anniversary update, the performance on my netbook has worsened, this is relating mainly to display and UI animations.
In my netbook, how it's possible that simply running the mouse over the Start menu's items or scrolling through the app list is so sluggish and makes the CPU go over 60%, by Windows Shell Experience Host and Desktop Window Manager, while the same thing on Windows 7 the CPU usage is almost 0 - 10%. How is that a simple thing as highlighting menu options or scrolling needs so much CPU compared to previous version?

In my desktop, the CPU usage is around 5% when hovering and 16% when scrolling, which IMO is still high for a relatively simple thing but no lagging.

The same thing happens to Office 2016, hovering over the toolbars you see a enormous lag in the highlighting effect and high CPU usage.

Can anyone explain this? Is maybe because of the composition engine given the DWM CPU usage

Thank you :)

Thank you

I did remove all tiles and resized the Start menu, leaving only the calendar and weather just after install W10 because the default start menu with all preinstalled metro apps was so huge it took almost all the small netbook screen when opened :) (and still is too big for the 1024x600 screen)

Also I did disabled all checkboxes in performance settings, leaving only shadow under cursor and smooth edges of screen fonts :)

TairikuOkami said:

All I can say, that after the upgrade, a browser was opening for 15 SECONDS, I have to use caps, because that was outrageous. After performing a maintenance and some tweaks, it dropped to 2 seconds. Try this, maybe it will help.

Run CMD as admin and copy/paste/enter:

chkdsk /scan
Dism /Online /Cleanup-Image /StartComponentCleanup /ResetBase
winmgmt /salvagerepository
del "%temp%\*" /s /f /q
del "C:\$Recycle.bin\*" /s /f /q
del "%systemroot%\temp\*" /s /f /q
vssadmin delete shadows /for=c: /all /quiet
cleanmgr /sageset:65535 & cleanmgr /sagerun:65535

Do not forget to perform HDD defrag with the software of your choice.

Optimize and Defrag Drives in Windows 10 - Windows 10 Forums

What do all these commands do?

You are wonderful. Thank you.
And I really love your "Be nice to all, please". Should be everyone's byline.