To handle high spikes in server traffic efficiently, you can implement various strategies on both the Apache and PHP sides. Here are some suggestions:

**Apache Configuration:**

1. **Optimize KeepAlive:** Configure Apache's KeepAlive settings to ensure that connections are reused efficiently, reducing the overhead of establishing new connections for each request.

2. **Increase ServerLimit and MaxClients:** If your server can handle it, increase the ServerLimit and MaxClients directives in your Apache configuration to allow more concurrent connections.

3. **Enable Caching:** Implement caching mechanisms like mod_cache and mod_cache_disk to cache static and dynamic content. This reduces the load on PHP-FPM and speeds up response times.

4. **Use Content Delivery Networks (CDNs):** Offload static content delivery to a CDN to reduce the load on your server and improve response times for users located far from your server.

5. **Implement Load Balancing:** If you have multiple servers, set up a load balancer to distribute incoming traffic evenly across them. This helps handle spikes in traffic more effectively by scaling horizontally.

**PHP Configuration:**

1. **Opcode Cache:** Enable an opcode cache like OPcache to cache compiled PHP code, reducing the overhead of parsing and compiling PHP scripts on each request.

2. **Optimize PHP-FPM Configuration:** Continuously fine-tune your PHP-FPM configuration based on your server's resources and traffic patterns, as we discussed earlier.

3. **Asynchronous Processing:** Offload long-running tasks to background processes or queues using tools like Gearman, RabbitMQ, or Redis to free up PHP-FPM processes to handle incoming requests.

4. **Code Optimization:** Regularly review and optimize your PHP code to improve its efficiency and reduce resource usage, such as database queries, file I/O, and memory consumption.

5. **Enable Gzip Compression:** Enable Gzip compression in PHP to reduce the size of data sent over the network, reducing bandwidth usage and speeding up page load times.

6. **Implement Rate Limiting:** Implement rate limiting to prevent abuse and mitigate the impact of sudden traffic spikes. Tools like mod_evasive for Apache can help with this.

By implementing these strategies, you can better handle high spikes in server traffic and ensure that your server remains responsive and available during peak loads.