Numbers documents open slowly from iCloud on all Apple devices

Why does opening a Numbers document saved on iCloud take ages? It’s not my internet, as it does the same on any network, even cellular. Every other file, be it pages pdfs or my cad files opens almost instantaneously, but 30seconds to literally 2 minutes for numbers.

This has been happening for a while, at least since iOS 17, for my wife and I. We are both on ios and iPadOS 18.7.2 and macOS 15.7.2. Most of our numbers documents are business documents, that are in a shared iCloud folder. I’ve tried saving directly to my computer, as well as other documents that are on my iCloud only, but nothing helps.

Unless I can see definitive proof that updating to 26 will solve this problem, we are happy on the versions we are on. I tried 26 in a VM, but since apple wont let me use the App Store in a VM, that doesn’t work.