Windows Booting very slow after 2004 update ,

@Bassthang - in addition to my previous post, here is a screenshot of Task Manager with Norton running a full system scan, and with the other minor disk activities (Firefox, and a few others) on the Desktop PC, it only sits at 25%, and this is with Malwarebytes active as well. The laptop has a less powerful HDD (less internal cache, slower spin speed), so that sits at 50% doing the same work.

Did you check out my other post about checking for "ghost" devices in Device Manager? Try out the HDD Guardian if you get chance, and review the SMART stats for your boot drive.

@Bassthang - If the HDD has been a 100% issue for the last 2 years that is an issue you need to look at. It may point to heavy "retries" due to data sectors being hard for the HDD internal controller to read, so it spends time re-trying reads to eventually get the data. The NTFS file system driver will do I/O retries too, if the HDD itself gives up on its own 512 or so "goes" at getting the data without ECC errors.

First, try looking at the device health under Disk Management (that is under Computer Management in the Control Panel, or you can find it from an icon "Manage"" in the "This PC" view.) Just check that your C: drive shows as Healthy.

You might want to get one of those SMART disk check utilities that can see the SMART disk error log statistics, for example HDD Guardian. That will give you a better idea of the drive state. If it  shows an issue, you might want to consider using Spinrite that a lot of IT Pros use to resurrect erroring HDD (and even SSD). 

See: https://www.grc.com/sr/spinrite.htm

Otherwise, check your startup items, to see if there is anything unexpected, like some scanner, or 2 anti-virus products fighting each other for access (there should only be one good one running ideally).

By the way, when you see 100% with Task manager (it needs at least 60 seconds to settle down, and wait for the System Interrupts to settle), did you try to ensure that the "view" was showing each item that makes up that 100%? Click on the disk percentage heading a couple of times to ensure it is sorted from highest to lowest. Even with a Norton full system scan running, mine only reaches 50%. if it is always 100%, something needs an in-depth review (like a Spinrite scan, or looking at the highest use process/program).

There was a ReadyBoot subfolder under prefetch which it would not let me delete. I was able to delete that folder's contents, though.

On restart, I didn't notice any improvement. The HDD is still maxed-out at 100% for ages (which has been a consistent problem with Win10 on this machine since an update two years ago). I noticed that Search was high up the Disk usage list, which is odd, as Search has been disabled in Services!

(And is apparently still disabled. . .).

I've been a Windows user since 3.0, but I think the time has come to give up on this OS. I'm fed up of spending hours every evening fighting with it to try and get it to function well enough to do a bit of work. Especially as with each new version of Windows, MS makes it harder to access tools (even Safe Mode is challenging to get to without finding step-by-step instructions on the web first) and get "under the bonnet" to fix things. It's completely unproductive to use. The 2004 update is the most troublesome yet for me. I'll be rolling it back to the previous build as soon as I've backed-up my files, and will probably go further and do a factory reset. (I've read articles about the benefits of doing a full clean install without the manufacturer's bloatware, but I'll try the factory reset first - the PC was great when it was new - only becoming slow and unrelaibale a few updates along.)

Similar issue for me.

Since the 2004 update, the boot times have increased to 5 minutes!!

Event viewer contains this entry, but I have no idea how to fix.

Quote = The winlogon notification subscriber <Profiles> took 266 second(s) to handle the notification event (Logon).

Just tried a Reboot. That took 8:50 to the point where OneDrive has completed checking for changes.

Yikes! That's worse than mine! Maybe the following directions TD47 will bring calmness into our lives. 

I have just installed the 2004 update and have encountered no problems fortunately.My boot time is 24  secs which is what it was before the update.

@JonGraef - those are useful observations and feedback. However, it seems that you ran the verifier, and then the sfc and dism commands. It is a shame that you did not run those 2 commands BEFORE running the verifier, and then run them again afterwards.

The problem might have been that as the verifier is designed to"stress test" drivers, it might result in unexpected things happening (especially if a Kernel Mode driver, or badly designed driver is being checked). Kernel mode can read and write anywhere, and MIGHT have ended up corrupting something, that THEN had to be fixed up by the sfc and dism commands.

Did you happen to note down WHAT items were found and fixed? Did BOTH commands find a problem?

It is always possible that this resulted in a "better" driver being used, than was there initially.  If you do have the info on what was fixed up, please post it here in case it is useful for others.

Sorry, but in the intensity of the moment I did not note what was fixed.

We can only hope that a Microsoft employee has the same issue on their home computers after the 2004 update. That was the action that broke things for ones posting in this thread.

I was really impressed with the robust nature of Windows 10, until 2004 update. Never had any issues with blue screen.....