Poor performance of Hailo8L and Rpi5

There are two points.

Your Raspberry Pi is set to PCI gen 2. Please follow this guide to upgrade it to PCIe gen 3.

How to upgrade to PCIe gen-3 in RPi5 with Hailo-8L M.2

The second point, the numbers in the Model Zoo are for a Hailo device connected to a system with 4 PCIe lanes and a x86 CPU. Your Raspberry Pi only has a single lane.

Especially for multi-context networks PCIe bandwidth will influence the maximum FPS you can reach.