completion script increases shell startup time considerably (zsh)

[Emerentius]

I've set up the completion script exactly as the instructions in rustup completions --help say:
added fpath += ~/.zfunc just before compinit in .zshrc
rustup completions zsh > ~/.zfunc/_rustup

Startup is noticeably slow. From my rough measurements, ~0.5s is added purely from the completion script.
This does not happen when I put it in another location on the fpath, like /usr/share/zsh/vendor-completions/.

[xaocon]

This is really old but I was looking for another bug so I wanted to ask. Is this still a problem for you? I notice you have fpath += ~/.zfunc in the description, maybe it's changed or maybe you typed it wrong but it should be fpath+=~/.zfunc.