Windows 10 SSD performance suddenly low after an update

SSD performance degraded after a Windows 10 update. Initially observed by a +30 second boot time increase and later confirmed with benchmarking tools.

Edit: Update most likely KB4038788 since it fits the approximate time I started noticing the issue.

Edit 2: KB4038788 was not the issue.

Specs:

Windows 10 Pro 15063.726

ASUS M5A97 R2.0 Motherboard. Latest BIOS (2603)

AMD FX-8350

8GB HyperX Fury 1866MHz (single channel)

Sapphire Nitro+ RX480

Seagate Barracuda drive, 1TB (ST1000DM003-1SB10C)

Maxtor 160GB drive (6Y160M0)

Sandisk Ultra II 240GB (SanDisk SDSSDHII240G) Latest Firmware X31200RL

Full MSInfo32 report here

Screencap of old benchmark prior to issue

Screencap of new benchmark after issue

Things I tried:

Unplugging all other drives.
Changing the SATA port and cable.
Changing the power cable.
Installing AMD chipset drivers.
Trimming. Both windows inbuilt and third party tools.
chkdsk /f
sfc /scannow
ntfsfix on a linux bootable.

Checking partition offsets:

C:\Users\Nexrem>wmic partition get BlockSize, StartingOffset, Name, Index
BlockSize  Index  Name                   StartingOffset
512        0      Disk #2, Partition #0  1048576
512        0      Disk #0, Partition #0  1048576
512        0      Disk #1, Partition #0  1048576
512        1      Disk #1, Partition #1  472907776
512        2      Disk #1, Partition #2  594542592

Uninstalling KB4038788.

Notes:

SSD and Seagate drive are running on AHCI mode, while Maxtor drive is on a port running on IDE.

Nexrem

Posted 2017-11-15T14:56:41.567

Reputation: 1

@Ramhound Looking at the update log seems to have been KB4038788. Edited. – Nexrem – 2017-11-15T15:05:36.880

@Ramhound Uninstalled KB4038788 and updated to 15063.726. Issue still persists. – Nexrem – 2017-11-15T15:26:15.340

@Ramhound seems so. Leads me back to a stump. Going to install the patch again. – Nexrem – 2017-11-15T16:14:24.017

@Ramhound It was an older screenshot I took for my mates back when I was benching the disk a month ago. After the slowdown I used that one as a reference. Switched to English in the meantime. – Nexrem – 2017-11-15T17:09:45.090

Feel feel to update your question with the information contained in your comments. – Ramhound – 2017-11-15T17:19:52.307

Updated. Also seems to have been solved with Fall Creators. Manually downloaded that and updated. Drive speeds back to normal. – Nexrem – 2017-11-15T17:54:49.997

You might want to record driver details (dates/version/ect.) so you can compare it to the details if the behavior resurfaces. Since Windows is being reinstalled with Feature Updates, strange things can happen with drivers, especially display drivers (the initial Nvidia driver included with the FCU had issues) – Ramhound – 2017-11-15T20:29:02.023