diff --git a/.changeset/many-worms-attend.md b/.changeset/many-worms-attend.md
new file mode 100644
index 000000000000..0da3699967f6
--- /dev/null
+++ b/.changeset/many-worms-attend.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: improve unowned derived performance
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index ff8eaa8ef9bc..27e174d3aa73 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -230,8 +230,9 @@ export function check_dirtiness(reaction) {
 			}
 		}
 
-		// Unowned signals should never be marked as clean.
-		if (!is_unowned) {
+		// Unowned signals should never be marked as clean unless they
+		// are used within an active_effect without skip_reaction
+		if (!is_unowned || (active_effect !== null && !skip_reaction)) {
 			set_signal_status(reaction, CLEAN);
 		}
 	}