Perf fixes

src/components/relative-time.jsx

@@ -8,7 +8,6 @@ import dayjs from 'dayjs';
 import dayjsTwitter from 'dayjs-twitter';
 import localizedFormat from 'dayjs/plugin/localizedFormat';
 import relativeTime from 'dayjs/plugin/relativeTime';
-import { useEffect, useState } from 'preact/hooks';
 
 dayjs.extend(dayjsTwitter);
 dayjs.extend(localizedFormat);
@@ -19,36 +18,19 @@ const dtf = new Intl.DateTimeFormat();
 export default function RelativeTime({ datetime, format }) {
   if (!datetime) return null;
   const date = dayjs(datetime);
-  const [dateStr, setDateStr] = useState('');
-
-  useEffect(() => {
-    let timer, raf;
-    const update = () => {
-      raf = requestAnimationFrame(() => {
-        let str;
-        if (format === 'micro') {
-          // If date <= 1 day ago or day is within this year
-          const now = dayjs();
-          const dayDiff = now.diff(date, 'day');
-          if (dayDiff <= 1 || now.year() === date.year()) {
-            str = date.twitter();
-          } else {
-            str = dtf.format(date.toDate());
-          }
-        } else {
-          str = date.fromNow();
-        }
-        setDateStr(str);
-
-        timer = setTimeout(update, 30_000);
-      });
-    };
-    raf = requestAnimationFrame(update);
-    return () => {
-      clearTimeout(timer);
-      cancelAnimationFrame(raf);
-    };
-  }, [date]);
+  let dateStr;
+  if (format === 'micro') {
+    // If date <= 1 day ago or day is within this year
+    const now = dayjs();
+    const dayDiff = now.diff(date, 'day');
+    if (dayDiff <= 1 || now.year() === date.year()) {
+      dateStr = date.twitter();
+    } else {
+      dateStr = dtf.format(date.toDate());
+    }
+  } else {
+    dateStr = date.fromNow();
+  }
 
   return (
     <time datetime={date.toISOString()} title={date.format('LLLL')}>

src/utils/nice-date-time.js

@@ -1,20 +1,32 @@
+import mem from './mem';
+
 const { locale } = new Intl.DateTimeFormat().resolvedOptions();
 
-function niceDateTime(date, { hideTime, formatOpts } = {}) {
-  if (!(date instanceof Date)) {
-    date = new Date(date);
-  }
+const _DateTimeFormat = (opts) => {
+  const { dateYear, hideTime, formatOpts } = opts || {};
   const currentYear = new Date().getFullYear();
-  const dateText = Intl.DateTimeFormat(locale, {
+  return Intl.DateTimeFormat(locale, {
     // Show year if not current year
-    year: date.getFullYear() === currentYear ? undefined : 'numeric',
+    year: dateYear === currentYear ? undefined : 'numeric',
     month: 'short',
     day: 'numeric',
     // Hide time if requested
     hour: hideTime ? undefined : 'numeric',
     minute: hideTime ? undefined : 'numeric',
     ...formatOpts,
-  }).format(date);
+  });
+};
+const DateTimeFormat = mem(_DateTimeFormat);
+
+function niceDateTime(date, dtfOpts) {
+  if (!(date instanceof Date)) {
+    date = new Date(date);
+  }
+  const DTF = DateTimeFormat({
+    dateYear: date.getFullYear(),
+    ...dtfOpts,
+  });
+  const dateText = DTF.format(date);
   return dateText;
 }