Slow Windows guest with 100% disk usage

[llamafilm]

For a long time I have suffered very slow performance in Windows 10 guests. Task Manager shows 100% disk usage although the speed is not very high. In this screenshot it's showing 45MBps read speed. The host is a MacBook Pro with flash storage over 1500MBps. I'm using a fixed size VDI. I'm currently on VirtualBox 5.2.22 but this has been happening for a long time across multiple versions. Is this a known issue and is there any way to make it access the disk image faster?

[socratis]

Moving to "Windows Guests" from "OSX Hosts".

this has been happening for a long time across multiple versions. Is this a known issue and is there any way to make it access the disk image faster?

Yes. Talk to Microsoft and see what the heck they're doing. I swear I'm going to get a screenshot of my physical Win10 installation and have it handy when a question like that comes up!

Having said that, there is one thing to check in your VM Settings » Storage » select your SATA controller » Use Host I/O Cache, check that.

[llamafilm]

Hi socratis. I'm not sure what you mean by this. I do not have this problem on real Windows machines. The slowness seems to be particularly bad anytime Windows Update or "antimalware service executable" is running, but I think this is simply because they do a lot of disk I/O.
I already have Host I/O cache enabled for the SATA AHCI controller.

[socratis]

I do not have this problem on real Windows machines

I do. Exactly that problem.

The slowness seems to be particularly bad anytime Windows Update or "antimalware service executable" is running

At this exact time. If you take a look at the Processes in the Task Manager, that's exactly what you see. And I'm still talking about my real PC.