diff --git a/src/bin/shared/getImplementedThemeTypes.ts b/src/bin/shared/getImplementedThemeTypes.ts
index 14af6de1..0a8955ab 100644
--- a/src/bin/shared/getImplementedThemeTypes.ts
+++ b/src/bin/shared/getImplementedThemeTypes.ts
@@ -4,9 +4,22 @@ import * as fs from "fs";
 import { type ThemeType } from "./constants";
 import { getThemeSrcDirPath } from "./getThemeSrcDirPath";
 
+type ImplementedThemeTypes = Readonly<Record<ThemeType | "email", boolean>>;
+
+let cache:
+    | { projectDirPath: string; implementedThemeTypes: ImplementedThemeTypes }
+    | undefined;
+
 export function getImplementedThemeTypes(params: { projectDirPath: string }) {
     const { projectDirPath } = params;
 
+    if (cache !== undefined && cache.projectDirPath === projectDirPath) {
+        const { implementedThemeTypes } = cache;
+        return { implementedThemeTypes };
+    }
+
+    cache = undefined;
+
     const { themeSrcDirPath } = getThemeSrcDirPath({
         projectDirPath
     });
@@ -19,5 +32,7 @@ export function getImplementedThemeTypes(params: { projectDirPath: string }) {
             ])
         );
 
+    cache = { projectDirPath, implementedThemeTypes };
+
     return { implementedThemeTypes };
 }