Here's another test. It shows that IPsec is more than 50% faster than WireGuard.
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https://www.pcwrt.com/2020/02/performance-comparisons-of-three-vpn-protocols-on-a-budget-router/
Thing is that WireGuard uses the ChaCha20 cipher which is very efficient and fast on non-dedicated hardware. IPsec, and sometimes also OpenVPN, can however often use hardware acceleration on AES and is then faster.
It's the devices in each end and their architecture (ARM, x86 etc) and any hardware offloading that will determine what to pick for maximum performance on a VPN. And often it just doesn't matter - for instance when the hardware can handle encryption at WAN speed.
Nice thing about WireGuard is that it has just been included in the 5.6 kernel so soon enough it will be available by default on every linux system.