OneDrive very slow in Windows Explorer

Problem: navigating my OneDrive folders in Windows Explorer is so slow as to be almost unusable. The problem appears to worsen as the working day progresses. This may be relevant to my working theory (see below).

Problem Behavior:

1. Double-clicking on any OneDrive file/folder in the left-hand folder tree window works fine, but if you right-click on anything, or single-click on its drop-down chevron, it brings up the "processing" blue circle icon, and the green loading-progress tape moves very slowly across the address bar at the top of the screen.
2. Selecting any operation in the right-click dropdown menu creates the same problem.
3. Right-clicking on a file or folder in the right-hand (main) window creates the same problem.

Each delay lasts 10-30 seconds. That is a lot longer than perhaps it sounds.

The only way to move between OneDrive folders in Explorer without triggering one of these delays is to left double-click. Moving files or folders must be done with drag-and-drop, not right-clicking; deleting files or folders must be done by navigating to the target item using keyboard arrow keys, then by using the DEL key, not a right-click action. Clearly this is unworkable nonsense.

The issue is confined to OneDrive folders in Explorer. Local drives, local detachable storage (like USB keys or externals) and other cloud storage destinations are all stable and responsive in the normal way.

My Downloads folder is periodically affected by latency issues also - particularly around loading of image files in MS Photo. This may or may not be relevant, so I am not detailing those here.

Rendering of previews for any file in any folder in Explorer is unreliable, and prone to slowness. Again, unsure if relevant.

Troubleshooting: I do not have the same problem when navigating OneDrive:

1. in a web browser on my Windows Desktop machine (Firefox, Chrome, Edge - all work fine)
2. on my MacBook Pro
3. from a mobile device

OneDrive is lightning fast and very stable in all these contexts. I have a venerable iPhone 7 (2016 model) and an even older iPad Air 2 (2014 vintage). Both handle OneDrive folder navigation just fine, both through local apps and online through a browser.

Clearly the issue is local, not server-side, and clearly it is peculiar to my Windows 10 Desktop installation.

Other details:

• I am also running DropBox and iCloud on all my devices. Both of these locations are lightning-fast in Windows Explorer, so this is evidently not a connectivity issue (and anyway, as noted above, the problem is also affecting my local Downloads folder - again, not a problem I am seeing on my MacBook).
• I have ample processing, storage and memory resources:

Processor: i9-9900K CPU @ 3.60GH

GPU: NVIDIA GeForce RTX 2080

Memory: 32Gb

Local Storage: 1TB SSD (OS) (25% used) / 4TB 7200RPM HD (Local OneDrive File Storage) (20% used)

• Yes, I am still running Windows 10, but - looking at relevant threads reporting the same issue - it appears the problem is also affecting Win11 users.
• I shut down my desktop machine at the end of each working day.

Working Theory: is this issue being caused by Windows Search Indexing in some way? I did observe Search Indexing consuming huge amounts of resource in Task Manager during a particularly bad episode. I investigated by pausing indexing and restarting Explorer and on one occasion this appeared to fix the problem, but there have been many other occasions when indexing was not going on in the background and yet the problem remained.

Microsoft: please step in and help us - it is clear from other threads here and on other boards that this is a widespread and longstanding issue.