Hard to tell from here, but we’ll start with where are your project files stored? Third party cloud storage? If so, which one. Do you have Apple iCloud “optimise disk storage” turned on?
I did copy the whole text and open a new file. Everything fine…but after a while and another copy-paste it broke down again…Scrivener changed the format ( just half the side ) and my text again is delaying…
Is your computer saving to iCloud? You can check this in your iCloud Settings. Are your Desktop and Documents folder saving to iCloud? If so, there is a cloud service at play so it’s possible that’s a factor.
Go to Scrivener → Settings → Editing and click the “Formatting” tab along the top. Set the default font formatting to how you want it to be—font, font size, indents, etc. Save your changes.
Click the Manuscript/Draft folder in the binder and go to View → Scrivenings. Put your cursor in the editor. Go to Edit -> Select All. All text in the editor should now be highlighted. Now, in Scrivener’s formatting toolbar (just above the editor), click on the paragraph styles dropdown and select “No Style” (even if it appears to already be selected). All formatting should now match what you set up in your Settings.
After doing this, do you still experience a typing lag?