Correlating requesta based on cookie: to sha or not to sha?

I want to be able to link various requests to my backend that are coming from same client. I came with adding header based on cookie:

backend servers
        description My backend

        http-request set-header Request-Id %[req.cook(AspNet,Session),sha1,hex]

        server srv_01

This is going to be used only for debug purposes when I want to find what user was doing. Should I be worried about performance? My cookie is around 300 bytes. There are also other hash functions (like xxh64 or wt6). Does it makes sense to use it?

Debian Buster, haproxy 2.2, ASP.Net Core as backend server.