Are there any pros/cons (especially performance-wise) ...

When considering the use of local storage as a replacement for cookies, particularly from a performance perspective, there are several pros and cons to take into account:

Pros of Using Local Storage:

1. Larger Storage Capacity: Local storage provides a much larger space to store data (around 5-10MB) compared to cookies, which are limited to about 4KB[1][2][3][4][5][6][7][8][9].

2. Client-Side Operations: Since local storage is accessible only by the client-side, it reduces server load and network traffic because the data is not sent with every HTTP request[1][2][3][4][5][6][7][8][9].

3. Persistent Data: Data stored in local storage does not have an expiration date and persists across browser sessions until it is explicitly cleared, either via JavaScript or by the user clearing the browser cache[1][2][3][4][5][6][7][8][9].

4. Performance: Local storage can lead to performance improvements since data does not need to be sent with each server request, reducing the amount of data transmitted over the network[1][2][3][4][5][6][7][8][9].

5. Data Types: Unlike cookies, which require data to be stored as strings, local storage can store any JavaScript object, although it is serialized to a string upon saving[1][2][3][4][5][6][7][8][9].

Cons of Using Local Storage:

1. No Server-Side Access: Data in local storage is not automatically sent to the server with each request, which means if the server needs access to this data, it must be sent explicitly, adding complexity to the client-server communication[1][2][3][4][5][6][7][8][9].

2. Security Risks: Local storage is vulnerable to cross-site scripting (XSS) attacks because the data can be accessed by any JavaScript code running on the page. If an attacker can inject malicious scripts, they can potentially read and steal data stored in local storage[1][2][3][4][5][6][7][8][9][10].

3. Limited Browser Support: Older browsers may not support local storage, or support may be inconsistent, which could limit the functionality of the website for users on older devices or browsers[1][2][3][4][5][6][7][8][9].

4. **No Bui...