Windows Booting very slow after 2004 update ,

Windows isn't becoming slower. That's a misconception !

I'm a programmer and I had (and still have) Windows 10 from it's first release. I've gone through all the updates and versions and the system kept it's parameters without exceptions.

Now I've installed v 2004, It's a fresh install because lately I've done some experiments with my PC and .... you get the picture.

The system has the same speed, with a slightly noticeable "pause" when you start a program or app than the 1909.

If you're still running on HDD, please change it immediately with an SSD.

Two things I've always done, right after a fresh install or major update of Windows:

1. Stopped and disabled SysMain service, or SuperFetch how it was called in early versions.
2. Stopped and disabled indexing service.

As a professional, I've never understood the role of SuperFetch (SysMain), other than keeping my drive bussy all the time. And the indexing service is just lame. I mean, if I don't know to organize and label my stuff it's my problem. That's my point of view, anyway.

Right after stopping SysMain, you drive will breath again. Trust me on this one.

IT WORKED !!!! Thank You! Thank you! Thank you!

Great, useful info from @LucianMinea. I did this on my desktop, that was suffering badly from horrible restart times, many instances of "Not Responding" stalls on browsers, office programs, and File Explorer itself, PLUS Task Manager showing very high System Interrupts for 10 to 15 seconds until it settled down, but still bursts form 6 to 12%.

After disabling the said services, everything went back to normal with retsart and boot times back to normal, and no "Not Responding" or other issues as mentioned above. The System Interrupts hog in Task Manager is NEVER seen now, and I only ever see around 0.1%

I can only conclude that there is a big conflict between the File Explorer interfaces, and the inter-related new Search and Search Indexing design that came in with 2004, along with the SysMain caching read/writes getting in the way.

NOTE: MUST also do a stop and change to manual on the Windows Media Player Network Sharing service too, IF running,  BEFORE stopping and disabling Windows Search service, as the dependency will slow down the stop of Windows Search, and risk a Blue Screen 133 bug-check in DPC_WATCHDOG.

I DO plan to change my systems to SSD at the end of the year, so should have even better performance, as he recomends.

I running a laptop with single hard drive bay - in order to upgrade I would need to buy a 1TB SSD hard drive, which I cannot afford to do this year. 

Basically, tough luck from Microsoft.

Hi, the problem seems to be HDD related, on 2 desktop PCs and one laptop, I have Windows of one desktop PC and the laptop on SSD, and the other desktop PC on HDD. The HDD desktop is slightly more powerful than the laptop but way less powerful than the ssd desktop. On both ssd systems boot load times and operations were mostly unaffected by the update. On the HDD desktop, it's now taking up to 5 minutes instead of 30-50 seconds to completely load everything on boot after the 2004 update. while loading everything while being booted up my HDD now sits at 100% and everything takes forever to load. SSDs are cheap enough now, my advice would just to get 1 120Gb or 240Gb ssd (even sata ones are fine) and to keep your hdd as more storage. Windows has moved on from being installed on HDD.

Windows isn't becoming slower. That's a misconception !

I'm a programmer and I had (and still have) Windows 10 from it's first release. I've gone through all the updates and versions and the system kept it's parameters without exceptions.

Now I've installed v 2004, It's a fresh install because lately I've done some experiments with my PC and .... you get the picture.

The system has the same speed, with a slightly noticeable "pause" when you start a program or app than the 1909.

If you're still running on HDD, please change it immediately with an SSD.

Two things I've always done, right after a fresh install or major update of Windows:

1. Stopped and disabled SysMain service, or SuperFetch how it was called in early versions.
2. Stopped and disabled indexing service.

As a professional, I've never understood the role of SuperFetch (SysMain), other than keeping my drive bussy all the time. And the indexing service is just lame. I mean, if I don't know to organize and label my stuff it's my problem. That's my point of view, anyway.

Right after stopping SysMain, you drive will breath again. Trust me on this one.