优化

app/src/main/java/io/legado/app/help/book/BookHelp.kt

@@ -154,7 +154,8 @@ object BookHelp {
         bookSource: BookSource,
         book: Book,
         bookChapter: BookChapter,
-        content: String
+        content: String,
+        concurrency: Int = AppConfig.threadCount
     ) = coroutineScope {
         flow {
             val matcher = AppPattern.imgPattern.matcher(content)
@@ -163,7 +164,7 @@ object BookHelp {
                 val mSrc = NetworkUtils.getAbsoluteURL(bookChapter.url, src)
                 emit(mSrc)
             }
-        }.onEachParallel(AppConfig.threadCount) { mSrc ->
+        }.onEachParallel(concurrency) { mSrc ->
             saveImage(bookSource, book, mSrc, bookChapter)
         }.collect()
     }

app/src/main/java/io/legado/app/model/CacheBook.kt

@@ -269,7 +269,7 @@ object CacheBook {
             if (BookHelp.hasContent(book, chapter)) {
                 Coroutine.async(executeContext = context) {
                     BookHelp.getContent(book, chapter)?.let {
-                        BookHelp.saveImages(bookSource, book, chapter, it)
+                        BookHelp.saveImages(bookSource, book, chapter, it, 1)
                     }
                 }.onSuccess {
                     onSuccess(chapter)

app/src/main/java/io/legado/app/ui/book/read/page/provider/TextChapterLayout.kt

@@ -27,6 +27,8 @@ import io.legado.app.utils.fastSum
 import io.legado.app.utils.splitNotBlank
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.Dispatchers.IO
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.ensureActive
 import kotlinx.coroutines.launch
@@ -83,7 +85,11 @@ class TextChapterLayout(
     var channel = Channel<TextPage>(Int.MAX_VALUE)
 
     init {
-        job = Coroutine.async(scope) {
+        job = Coroutine.async(
+            scope,
+            start = CoroutineStart.LAZY,
+            executeContext = IO
+        ) {
             launch {
                 val bookSource = book.getBookSource() ?: return@launch
                 BookHelp.saveImages(bookSource, book, bookChapter, bookContent.toString())
@@ -95,6 +101,7 @@ class TextChapterLayout(
         }.onFinally {
             isCompleted = true
         }
+        job.start()
     }
 
     fun setProgressListener(l: LayoutProgressListener?) {