diff --git a/__tests__/helpers.ts b/__tests__/helpers.ts
index df3c154..05ad2a3 100644
--- a/__tests__/helpers.ts
+++ b/__tests__/helpers.ts
@@ -48,16 +48,16 @@ test("extractParamNameUnion", () => {
 
   expect(extractParamNameUnion("foo{}")).toStrictEqual({
     name: "foo",
-    union: [],
+    union: new Set([]),
   });
 
   expect(extractParamNameUnion("foo{a}")).toStrictEqual({
     name: "foo",
-    union: ["a"],
+    union: new Set(["a"]),
   });
 
   expect(extractParamNameUnion("foo{a|b}")).toStrictEqual({
     name: "foo",
-    union: ["a", "b"],
+    union: new Set(["a", "b"]),
   });
 });
diff --git a/__tests__/matcher.ts b/__tests__/matcher.ts
index 4338617..13792c4 100644
--- a/__tests__/matcher.ts
+++ b/__tests__/matcher.ts
@@ -45,7 +45,7 @@ test("getMatcher returns a proper matcher structure for paths with params (in pa
     path: [
       "projects",
       { name: "projectId" },
-      { name: "env", union: ["live", "sandbox"] },
+      { name: "env", union: new Set(["live", "sandbox"]) },
     ],
     search: undefined,
   });
@@ -67,8 +67,8 @@ test("getMatcher returns a proper matcher structure for paths with params (in pa
     ranking: 16,
     path: ["group", { name: "groupId" }],
     search: {
-      foo: { multiple: false, union: ["a", "b"] },
-      bar: { multiple: true, union: ["c", "d"] },
+      foo: { multiple: false, union: new Set(["a", "b"]) },
+      bar: { multiple: true, union: new Set(["c", "d"]) },
     },
   });
 });
@@ -114,11 +114,11 @@ test("getMatcher decrements the ranking by 1 if the path is an area", () => {
       search: {
         orderBy: {
           multiple: false,
-          union: ["asc", "desc"],
+          union: new Set(["asc", "desc"]),
         },
         status: {
           multiple: true,
-          union: ["disabled", "enabled", "pending"],
+          union: new Set(["disabled", "enabled", "pending"]),
         },
       },
     },
diff --git a/package.json b/package.json
index 5cbc3a8..205ea34 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@swan-io/chicane",
-  "version": "2.2.0",
+  "version": "2.2.1",
   "license": "MIT",
   "packageManager": "pnpm@10.12.1",
   "description": "A simple and safe router for React and TypeScript",
diff --git a/src/createRouter.ts b/src/createRouter.ts
index 79670bd..3c37684 100644
--- a/src/createRouter.ts
+++ b/src/createRouter.ts
@@ -102,10 +102,13 @@ export const createRouter = <
     const matchersKey = JSON.stringify(routeNames);
 
     const matchers = useMemo(
-      () =>
-        rankedMatchers.filter(({ name }) =>
-          routeNames.includes(name as RouteName),
-        ),
+      () => {
+        const routeNamesSet = new Set(routeNames);
+
+        return rankedMatchers.filter(({ name }) =>
+          routeNamesSet.has(name as RouteName),
+        );
+      },
       [matchersKey], // eslint-disable-line react-hooks/exhaustive-deps
     );
 
@@ -133,8 +136,10 @@ export const createRouter = <
     const locationObject =
       location != null ? decodeLocation(location) : getLocation();
 
+    const routeNamesSet = new Set(routeNames);
+
     const matchers = rankedMatchers.filter(({ name }) =>
-      routeNames.includes(name as RouteName),
+      routeNamesSet.has(name as RouteName),
     );
 
     // @ts-expect-error
diff --git a/src/helpers.ts b/src/helpers.ts
index 14a59ac..0bc81b0 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -40,16 +40,18 @@ export const areRouteEqual = (
 
 export const extractParamNameUnion = (
   paramName: string,
-): { name: string; union?: string[] } => {
+): { name: string; union?: Set<string> } => {
   const bracketIndex = paramName.indexOf("{");
 
   if (bracketIndex > -1 && paramName.endsWith("}")) {
     return {
       name: paramName.substring(0, bracketIndex),
-      union: paramName
-        .substring(bracketIndex + 1, paramName.length - 1)
-        .split("|")
-        .filter(isNonEmpty),
+      union: new Set(
+        paramName
+          .substring(bracketIndex + 1, paramName.length - 1)
+          .split("|")
+          .filter(isNonEmpty),
+      ),
     };
   } else {
     return { name: paramName };
diff --git a/src/matcher.ts b/src/matcher.ts
index c28b953..4a5b8b1 100644
--- a/src/matcher.ts
+++ b/src/matcher.ts
@@ -103,7 +103,7 @@ export const getMatchResult = (
 
     const { name, union } = test;
 
-    if (union == null || union.includes(part)) {
+    if (union == null || union.has(part)) {
       pathParams[name] = part;
     } else {
       return;
@@ -123,7 +123,7 @@ export const getMatchResult = (
       const parts = typeof part === "string" ? [part] : part;
 
       const values =
-        union == null ? parts : parts.filter((item) => union.includes(item));
+        union == null ? parts : parts.filter((item) => union.has(item));
 
       if (multiple) {
         searchParams[key] = values;
@@ -185,12 +185,12 @@ export const matchToUrl = (matcher: Matcher, params: Params = {}): string => {
       const { union } = test;
 
       if (typeof param === "string") {
-        if (union == null || union.includes(param)) {
+        if (union == null || union.has(param)) {
           object[key] = param;
         }
       } else {
         object[key] =
-          union == null ? param : param.filter((item) => union.includes(item));
+          union == null ? param : param.filter((item) => union.has(item));
       }
     }
 
diff --git a/src/types.ts b/src/types.ts
index 8f90357..138a472 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -9,8 +9,10 @@ export type Matcher = {
   name: string;
   ranking: number;
 
-  path: (string | { name: string; union?: string[] })[];
-  search: Record<string, { multiple: boolean; union?: string[] }> | undefined;
+  path: (string | { name: string; union?: Set<string> })[];
+  search:
+    | Record<string, { multiple: boolean; union?: Set<string> }>
+    | undefined;
 };
 
 export type RouteObject = Readonly<{