Large attachment upload impacts XWiki responsiveness

Prerequisites:

• Have prepared in advance a large attachment (i.e archive large than 1GB)

Steps to reproduce:

1. Navigate to the Sandbox Test page.
2. Upload a large file via the Attachments section — either by drag-and-drop or using the file explorer.
3. While the upload is in progress, attempt to perform other actions in XWiki (e.g., switch pages, open a new tab, or start editing).

Actual Result:

During the file upload, other XWiki actions become unresponsive. Pages outside the upload context appear blank, and the platform becomes nearly unusable. Near 99% of the upload progress, XWiki may freeze entirely for all operations.

Expected Result:

Uploading a large file should not block or freeze other XWiki operations. The platform should remain responsive and usable during the upload process.