You are managing a globally accessible apparel website using Cloud Spanner. Despite the global reach, you've encountered read latency issues on a specific table accessed solely via its primary key. The table's schema is as follows:

CREATE TABLE Users (
    user_id INT64 NOT NULL, // Sequential number based on registration
    account_creation_date DATE, // System date
    firstname STRING(255), // First name
    lastname STRING(255), // Last name
    birthdate DATE, // User birthdate
    profile_picture BYTES(255) // User profile picture
) PRIMARY KEY (user_id)

What action should you take to mitigate these performance issues?