Fixed: Speed up book api

src/NzbDrone.Core/Datastore/Migration/022_edition_monitored_index.cs

@@ -0,0 +1,14 @@
+using FluentMigrator;
+using NzbDrone.Core.Datastore.Migration.Framework;
+
+namespace NzbDrone.Core.Datastore.Migration
+{
+    [Migration(22)]
+    public class EditionMonitoredIndex : NzbDroneMigrationBase
+    {
+        protected override void MainDbUpgrade()
+        {
+            Create.Index().OnTable("Editions").OnColumn("Monitored");
+        }
+    }
+}

src/Readarr.Api.V1/Books/BookController.cs

@@ -1,6 +1,6 @@
-using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
 using FluentValidation;
 using Microsoft.AspNetCore.Mvc;
 using NzbDrone.Common.Extensions;
@@ -70,10 +70,13 @@ namespace Readarr.Api.V1.Books
         {
             if (!authorId.HasValue && !bookIds.Any() && titleSlug.IsNullOrWhiteSpace())
             {
+                var editionTask = Task.Run(() => _editionService.GetAllMonitoredEditions());
+                var metadataTask = Task.Run(() => _authorService.GetAllAuthors());
                 var books = _bookService.GetAllBooks();
 
-                var authors = _authorService.GetAllAuthors().ToDictionary(x => x.AuthorMetadataId);
-                var editions = _editionService.GetAllMonitoredEditions().GroupBy(x => x.BookId).ToDictionary(x => x.Key, y => y.ToList());
+                var editions = editionTask.GetAwaiter().GetResult().GroupBy(x => x.BookId).ToDictionary(x => x.Key, y => y.ToList());
+
+                var authors = metadataTask.GetAwaiter().GetResult().ToDictionary(x => x.AuthorMetadataId);
 
                 foreach (var book in books)
                 {

src/Readarr.Api.V1/Books/BookControllerWithSignalR.cs

@@ -112,10 +112,14 @@ namespace Readarr.Api.V1.Books
 
         private void LinkAuthorStatistics(List<BookResource> resources, List<AuthorStatistics> authorStatistics)
         {
+            var bookStatsDict = authorStatistics.SelectMany(x => x.BookStatistics).ToDictionary(x => x.BookId);
+
             foreach (var book in resources)
             {
-                var stats = authorStatistics.SingleOrDefault(ss => ss.AuthorId == book.AuthorId);
-                LinkAuthorStatistics(book, stats);
+                if (bookStatsDict.TryGetValue(book.Id, out var stats))
+                {
+                    book.Statistics = stats.ToResource();
+                }
             }
         }