Staring a word with multiple forward slashes in msys2 in windows is causing slowdown of terminal

[AnonymousYoda]

Like while using "ml //help", as soon as i type h the terminal slows down and it takes a while till complete word is displayed

[helmesjo]

For me it freezes, but so far I've only been able to replicate it when run under alacritty + Msys2.

Reproduce:

1. Setup.

$ winget install Alacritty
$ winget install MSYS2.MSYS2
# Start "MSYS2 UCRT64" terminal
$ pacman install git zsh
$ mkdir ~/.zsh
$ git clone https://github.com/zsh-users/zsh-syntax-highlighting ~/.zsh/zsh-syntax-highlighting

2. Run the following command to start alacritty with msys2 & zsh:

alacritty.exe --command "C:/msys64/msys2_shell.cmd -ucrt64 -defterm -here -no-start -use-full-path -shell zsh"

4. Clone & source syntax-highlighting

git clone 
source ~/.zsh/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh
# then try double forward slash (if you're quick you'll get some extra
# characters in, suggesting this is happening in some async part):
cd //qwd # it's now frozen

Edit
Actually, when making this reproducer I noticed that it also happens without alacritty as well.