diff --git a/pkgs/shells/zsh/default.nix b/pkgs/shells/zsh/default.nix
index 5af94223ec83..300f685b981b 100644
--- a/pkgs/shells/zsh/default.nix
+++ b/pkgs/shells/zsh/default.nix
@@ -54,7 +54,7 @@ stdenv.mkDerivation {
     "--enable-pcre"
     "--enable-zshenv=${placeholder "out"}/etc/zshenv"
     "--disable-site-fndir"
-    "--enable-function-subdirs"
+    # --enable-function-subdirs is not enabled due to it being slow at runtime in some cases
   ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform && !stdenv.hostPlatform.isStatic) [
     # Also see: https://github.com/buildroot/buildroot/commit/2f32e668aa880c2d4a2cce6c789b7ca7ed6221ba
     "zsh_cv_shared_environ=yes"