performance: cache Intl instances (#894)

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Not released
 
+- cache Intl instances to improve performance [#894](https://github.com/CartoDB/carto-react/pull/894)
 - Support for `onRowMouseEnter` and `onRowMouseLeave` handlers for Table Widget [#907](https://github.com/CartoDB/carto-react/pull/907)
 
 ## 3.0.0

packages/react-ui/src/hooks/useImperativeIntl.js

@@ -8,22 +8,40 @@ import {
 } from '../localization/localeUtils';
 
 const cache = createIntlCache();
+const intlInstanceCache = new WeakMap();
 
-export default function useImperativeIntl(intlConfig) {
-  return useMemo(() => {
-    const locale = intlConfig?.locale || DEFAULT_LOCALE;
-    const messagesLocale = findMatchingMessagesLocale(locale, messages);
-    const intMessages = {
-      ...(messages[messagesLocale] || {}),
-      ...(intlConfig?.messages || {})
-    };
+const createIntlInstance = (intlConfig) => {
+  const locale = intlConfig?.locale || DEFAULT_LOCALE;
+  const messagesLocale = findMatchingMessagesLocale(locale, messages);
+  const intMessages = {
+    ...(messages[messagesLocale] || {}),
+    ...(intlConfig?.messages || {})
+  };
+
+  const combinedMessages = flattenMessages(intMessages);
+  return createIntl(
+    {
+      locale,
+      messages: combinedMessages
+    },
+    cache
+  );
+};
 
-    return createIntl(
-      {
-        locale,
-        messages: flattenMessages(intMessages)
-      },
-      cache
-    );
-  }, [intlConfig]);
+const getGloballyCachedIntl = (intlConfig) => {
+  // This is very simple cache exploits fact that Intl instance is actually same for most of time
+  // so we can reuse those maps across several instances of same components
+  // note, useMemo can't cache accross many that globally and flattenMessages over _app_ and c4r messages is quite costly
+  // and would be paid for every c4r component mounted.
+  let cachedInstance = intlInstanceCache.get(intlConfig);
+  if (cachedInstance) {
+    return cachedInstance;
+  }
+  const newInstance = createIntlInstance(intlConfig);
+  intlInstanceCache.set(intlConfig, newInstance);
+  return newInstance;
+};
+
+export default function useImperativeIntl(intlConfig) {
+  return getGloballyCachedIntl(intlConfig);
 }