Tested the performance with:
> time cmake -DJSON_SOURCE_PATH=src/secp256k1/src/wycheproof/ecdsa_secp256k1_sha256_bitcoin_test.json -DHEADER_PATH=build/after/ecdsa_secp256k1_sha256_bitcoin_test.json -P cmake/script/GenerateHeaderFromJson.cmake
Before:
> 3.57s user 6.01s system 94% cpu 10.136 total
After:
> 0.17s user 0.01s system 98% cpu 0.187 total