Using Fiat-Shamir, an interactive 3-round sigma protocol can be compiled into a non-interactive zero-knowledge proof in the random oracle model.
A NIZK through Fiat-Shamir is not UC-Secure due to rewinding. There are some straight-line-extractable compilation techniques, and to the best of my knowledge, the most efficient one is the proof-of-work-based Fischlin transform.
My question is about the computational performance differences. Specifically, for 128 security, how much slower will it be compared to Fiat-Shamir "in practice" to do a NIZK proof of knowledge of discrete log? Like 20 times slower, or 20000 times slower? Select whatever Fischlin parameters (like the length of the hash, iterations, etc) necessary for optimal results