Will the internet be slow during the Nice Carnival parades?

You should set realistic expectations. During the peak of the Carnival, especially during the Flower Parade (Bataille de Fleurs) or the Carnival Parade of Lights, the local networks along the Promenade des Anglais and Place Masséna are under extreme strain from tens of thousands of people. While our eSIM uses the best local networks, you should expect data to be slower than normal during these peak hours. It will still be far more reliable for sending messages and light browsing than any congested public Wi-Fi.