FastClick - A faster version of the Click Modular Router featuring batching, advanced multi-processing and improved Netmap and DPDK support (ANCS'15). Check the metron branch for Metron specificities (NSDI'18). PacketMill modifications (ASPLOS'21) as well as MiddleClick(ToN, 2021) are merged in main.
Why do you think that https://github.com/zerotier/ZeroTierOne is a good alternative to fastclick