chore: improve signal runtime perf (#12093)

* chore: improve signal runtime perf

* chore: improve signal runtime perf

* chore: improve signal runtime perf

.changeset/sweet-bottles-check.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+chore: improve runtime performance of capturing reactive signals

packages/svelte/src/internal/client/runtime.js

@@ -357,11 +357,7 @@ export function execute_reaction_fn(signal) {
 
 					if (reactions === null) {
 						dependency.reactions = [signal];
-					} else if (reactions[reactions.length - 1] !== signal) {
+					} else if (reactions[reactions.length - 1] !== signal && !reactions.includes(signal)) {
-						// TODO: should this be:
-						//
-						// } else if (!reactions.includes(signal)) {
-						//
 						reactions.push(signal);
 					}
 				}