We've added Fastcraft to a modpack hosted on FTB called Direstein. The server is hosted from my home.
My friends and I have been testing this modpack and server for several weeks prior to gathering the permissions for a Private (apply/invite only) server and modpack instance. We had to install a test version when we decided to also use Forge Essentials (Fastcraft-1.22-ctest8.jar). This test version of Fastcraft has performed without any issues and the same noticeable improvements to performance on both server and clients.
Thank you for developing this mod! We've been playing around with this modpack trying to get it off the ground for some time, but had old hardware. I wasn't sure that it would be worth investing in new given that it could have been the 130+ mods we wanted to use until installing Fastcraft, but the improvement to the old server (now going to be used as a Dev) were so substantial I was convinced to spend the money. 