Why This Comparison Matters

The Raspberry Pi 4 became the embedded community's workhorse for good reason: it offered four Cortex-A72 cores, up to 8 GB LPDDR4, gigabit Ethernet, and USB 3.0 in a familiar 85 x 56 mm form factor at an accessible price. The Pi 5 raises the bar significantly, and understanding exactly where the gains land — and where they do not — is essential before committing to either platform for a new product.

CPU and Memory Bandwidth

The Pi 5 replaces the Cortex-A72 with a Cortex-A76 cluster, a microarchitecture generation newer with a substantially deeper out-of-order window and improved branch prediction. Clock for clock the A76 delivers roughly 2-3x IPC improvement over the A72 on integer workloads. Clocked at 2.4 GHz versus the Pi 4's 1.8 GHz, the real-world single-thread speedup is approximately 2.5x.

LPDDR4X at 4267 MT/s on the Pi 5 (versus LPDDR4 at 3200 MT/s on the Pi 4) also improves memory bandwidth significantly — relevant for any workload that processes frame buffers, sensor streams, or large model weights.

I/O — Where the Pi 5 Changes the Game

The Pi 5 introduces the RP1 south bridge chip, which moves USB 3.0 and Ethernet off the SoC's single PCIe 2.0 lane (shared with USB on Pi 4) onto a dedicated PCIe 2.0 x4 link. The practical result: simultaneous USB 3.0 and Gigabit Ethernet no longer compete for bandwidth. Sustained disk throughput through a USB 3.0 NVMe adapter improves from ~350 MB/s on Pi 4 to ~450 MB/s on Pi 5.

The Pi 5 also exposes a PCIe 2.0 x1 connector (via the FFC slot), enabling direct NVMe SSDs or custom PCIe peripherals — a first for the platform.

GPIO and Real-Time I/O

Both boards expose the same 40-pin HAT header, but the Pi 5's RP1 changes the GPIO implementation. GPIO on Pi 4 is handled directly by the BCM2711 SoC with low and predictable latency. On Pi 5, GPIO goes through the RP1 over PCIe, which introduces additional latency that can affect bit-banged protocols. For timing-sensitive GPIO applications (software SPI, 1-Wire, IR), measure your specific use case on Pi 5 before committing.

Both platforms benefit from PREEMPT_RT for hard real-time requirements, but the Pi 4's direct GPIO path gives it an edge for latency-critical bare-metal-style operations.

Power and Thermal

The Pi 5 draws more power — expect 5-8 W under sustained CPU load versus 3-6 W for the Pi 4. The Pi 5 requires a 5V 5A (27W) USB-C supply; the Pi 4's 3A supply will work but trigger an undervoltage warning under full load. Thermal management is more critical on the Pi 5 — a heatsink is effectively mandatory for sustained workloads, and the official active cooler is recommended for AI inference or video processing applications.

Real-World Benchmark Summary

• 7-zip compression: Pi 5 is ~2.4x faster
• Python inference (MobileNetV2, ONNX): Pi 5 is ~2.8x faster
• OpenCV frame processing (1080p): Pi 5 is ~2.2x faster
• SQLite read throughput: Pi 5 is ~1.8x faster
• GPIO toggle latency (software): Pi 4 has lower worst-case with RT kernel

Which to Choose?

Choose the Pi 5 if your application is CPU or memory-bandwidth bound — AI inference, video processing, complex data pipelines, or anything that currently struggles for performance on Pi 4. Choose the Pi 4 if GPIO timing precision is paramount, power budget is tight, or if you need the ecosystem stability of a platform that has been shipping for five years. Both are excellent — the choice is workload-specific.