The Inspection Spectrum

Not all firewalling is created equal. The more 'layers' the firewall uncurls, the more CPU cycles it consumes.

The TLS Decryption Tax

Today, >90% of web traffic is encrypted (HTTPS). To inspect this traffic for malware, the firewall must perform a Man-in-the-Middle (MITM) decryption:

1. Intercept the client's handshake.
2. Decrypt the traffic using a local certificate.
3. Inspect the payload.
4. Re-encrypt the traffic for the destination.

This process is computationally expensive. Enabling full TLS Decryption can drop a firewall's rated throughput by 50% to 80%.

Performance Optimizations

• Hardware Offload (ASICs/FPGA): Moving encryption and pattern matching into dedicated chips.
• Single-Pass Architecture: Performing all security checks (AV, IPS, App Control) in a single unified scan rather than serial processing.

Conclusion

A firewall is a compromise between safety and speed. By understanding where your bottlenecks lie—whether in CPU-bound encryption or packet-header logic—you can design a perimeter that protects without choking the business.