What are the differences between deferred mode and normal data loading?

Lazy loading mode differs from regular loading in that data or resources are not loaded immediately upon initialization, but only at the moment of their direct use.

Regular loading implies that all necessary data are loaded in advance, for example, when starting the application or opening a screen. This can lead to long waiting times and high memory consumption.

Lazy loading allows saving resources and speeding up startup by loading data as needed. For example, in iOS, this is often used when loading images in a table — images are loaded only when the cell becomes visible.

Example in Swift with lazy image loading:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
    let imageURL = imageURLs[indexPath.row]
    // Lazy image loading
    loadImageAsync(from: imageURL) { image in
        DispatchQueue.main.async {
            cell.imageView?.image = image
            cell.setNeedsLayout()
        }
    }
    return cell
}