diff --git a/src/modules/disable.rs b/src/modules/disable.rs
index 5ce3ee4..73f568e 100644
--- a/src/modules/disable.rs
+++ b/src/modules/disable.rs
@@ -2,11 +2,19 @@
 //! `disabled_commands = LIST WHO KNOCK` (space-separated; repeatable). A disabled
 //! command replies with `421` as if it didn't exist. Off unless configured.
 
+use crate::map::HashSet;
 use crate::module::{ModResult, Module};
 use crate::numeric::ERR_UNKNOWNCOMMAND;
 use crate::server::Server;
 use crate::Uid;
 
+/// The disabled-command set, parsed once and re-parsed only when the config changes.
+#[derive(Default)]
+struct DisabledCache {
+    gen: u64,
+    cmds: HashSet<String>, // uppercased command names
+}
+
 pub struct Disable;
 
 impl Module for Disable {
@@ -25,11 +33,22 @@ impl Module for Disable {
         if srv.is_oper(uid) {
             return ModResult::Passthru;
         }
+        // (re)build the set only when the config generation changes, not per command
+        let gen = srv.config_gen;
+        let stale = srv.ext.get::<DisabledCache>().map(|c| c.gen != gen).unwrap_or(true);
+        if stale {
+            let cmds: HashSet<String> = srv
+                .conf_all("disabled_commands")
+                .iter()
+                .flat_map(|line| line.split_whitespace())
+                .map(|c| c.to_ascii_uppercase())
+                .collect();
+            srv.ext.set(DisabledCache { gen, cmds });
+        }
         let disabled = srv
-            .conf_all("disabled_commands")
-            .iter()
-            .flat_map(|line| line.split_whitespace())
-            .any(|c| c.eq_ignore_ascii_case(cmd));
+            .ext
+            .get::<DisabledCache>()
+            .is_some_and(|c| c.cmds.contains(&cmd.to_ascii_uppercase()));
         if disabled {
             srv.numeric(
                 uid,