General Random Write disk speed degradation in Windows 11.

So I wonder if it makes sense to break up by 2 TB SSD Disk into a windows partition and then a separate data partition (right now I just have one big undivided disk)? But then I'll have to rebuild everything. Nah -- too much work. Hopefully MS will fix this.

Also, I wonder if most review sites test these drives where windows is not installed on it? Which bumps up the numbers.

Another thing is -- is this purely a Windows 11 issue. In other words, if Windows 10 was the SSD drive, was performance degraded? Or only in Windows 11?

@eapLM,

Yes, the problem is just with windows 11.

Same exact configuration and same machine with windows 10 and windows 11, Windows 10 does not show this problem.

You can see in my previous posts the different results for Windows 10 versus Windows 11.

For me, and I have seen others on Reddit, this issue is not present on Windows 10 and people started noticing this issue after upgrading or installing Windows 11.

I've spent the last 8 hours or so banging my head on this one and finally just now found this thread. Nice to know at least that I'm not alone.

I've confirmed this issue on 2 different machines with 3 different NVME drive models. Confirmed in PCI-E 4.0 and 3.0 slots. Confirmed it only affects a disk when Windows is installed on that disk. Only random writes are affected, sequential is normal.

But furthermore, something I haven't seen mentioned yet, is that it affects not necessarily just the disk where Windows is installed, but any partition containing a Windows installation.

Create multiple partitions on the same disk and only the one where Windows is installed will have the problem. It doesn't have to be the Windows installation currently loaded either. I have installed Windows on 2 different disks in the same system. Regardless of which installation I boot into, both Windows partitions have the issue, none of the other partitions on the same disks have a problem.

Screenshot is tests from 2 different partitions on the same 980 Pro (first one has the Windows installation):

Windows 11 OS Build 22000.348 this issue is still present. See below 2 screen shots. The 1st one is Samsung 980 Pro 2TB as second drive, all performance is according to specifications of the drive. The 2nd one is the same Samsung 980 Pro 2TB drive but now as primary drive with Windows installed on the drive. Both screenshots are made on the same system and on the same drive.

Samsung 980 Pro 2TB - second drive, Windows on another drive - no problem with (4K) Random Write IOPS

Samsung 980 Pro 2TB - primary drive, Windows on this drive - 60% reduction in (4K) Random Write IOPS

I really hope Microsoft can fix this problem asap.

I'm having the same issue. I have two 1T Samsung 980 Pro's in my system with X570 + 5950X. The system drive (top image) uses the PCIE lane from the CPU, the D drive (bottom image) uses the chipset lane. The performance of the D drive is unaffected, but write IOPS and write Q32T16 of the C drive is much slower. The windows 11 is a fresh install from the ISO, reinstalling windows 10 resolves the problem, so it's not caused by the disk.