Fix playback performance on long texts

src/lib/reading.ts

@@ -36,6 +36,32 @@ export function getTimingMultiplier(text: string, adaptiveTiming: boolean): numb
   return multiplier;
 }
 
+export function getTimingMultiplierForWords(
+  words: string[],
+  startIndex: number,
+  endIndex: number,
+  adaptiveTiming: boolean,
+): number {
+  if (!adaptiveTiming) return 1;
+  if (endIndex <= startIndex) return 1;
+
+  let maxLen = 0;
+  for (let i = startIndex; i < endIndex; i++) {
+    const w = words[i];
+    if (w && w.length > maxLen) maxLen = w.length;
+  }
+  let multiplier = 1 + Math.sqrt(maxLen) * 0.04;
+
+  const lastToken = words[endIndex - 1] || "";
+  const last = stripTrailingClosers(lastToken);
+  if (/[.!?]$/.test(last)) {
+    multiplier = Math.max(multiplier, 2.5);
+  } else if (/[,;:]$/.test(last)) {
+    multiplier = Math.max(multiplier, 1.8);
+  }
+  return multiplier;
+}
+
 export function getWordDelay(
   text: string,
   baseDelayMs: number,
@@ -44,6 +70,19 @@ export function getWordDelay(
   return baseDelayMs * getTimingMultiplier(text, adaptiveTiming);
 }
 
+export function getWordDelayForWords(
+  words: string[],
+  startIndex: number,
+  endIndex: number,
+  baseDelayMs: number,
+  adaptiveTiming: boolean,
+): number {
+  return (
+    baseDelayMs *
+    getTimingMultiplierForWords(words, startIndex, endIndex, adaptiveTiming)
+  );
+}
+
 export function formatReadingTime(minutes: number): string {
   minutes = Math.round(minutes);
   if (minutes < 1) return "< 1 min";