Problem with speed of proxies in google cloud

Question

I have hosted a server in google cloud located in Frankfurt in order to have the lowest possible latency to a web page that is hosted there as well. I have a few German proxies to be able to access that page also with them, but the problem is that I have very high speeds (150ms) using those proxies, when a friend has used them too and has achieved much lower speeds (50ms).

I have 8 cores with 16 GB of ram on the server, but I don't know what the problem is. Is there a google cloud configuration that is making it have such high speeds?