diff --git a/src/NzbDrone.Core.Test/MediaCoverTests/ImageResizerFixture.cs b/src/NzbDrone.Core.Test/MediaCoverTests/ImageResizerFixture.cs
index a7d9639f7..fcec07b32 100644
--- a/src/NzbDrone.Core.Test/MediaCoverTests/ImageResizerFixture.cs
+++ b/src/NzbDrone.Core.Test/MediaCoverTests/ImageResizerFixture.cs
@@ -4,7 +4,9 @@
 using Moq;
 using NUnit.Framework;
 using NzbDrone.Common.Disk;
+using NzbDrone.Common.EnvironmentInfo;
 using NzbDrone.Core.Test.Framework;
+using SixLabors.ImageSharp;
 
 namespace NzbDrone.Core.Test.MediaCoverTests
 {
@@ -14,13 +16,10 @@ public class ImageResizerFixture : CoreTest<MediaCover.ImageResizer>
         [SetUp]
         public void SetUp()
         {
-            Mocker.GetMock<IDiskProvider>()
-                  .Setup(v => v.OpenReadStream(It.IsAny<string>()))
-                  .Returns<string>(s => new FileStream(s, FileMode.Open));
-
-            Mocker.GetMock<IDiskProvider>()
-                  .Setup(v => v.OpenWriteStream(It.IsAny<string>()))
-                  .Returns<string>(s => new FileStream(s, FileMode.Create));
+            if (PlatformInfo.IsMono && PlatformInfo.GetVersion() < new Version(5, 8))
+            {
+                Assert.Inconclusive("Not supported on Mono < 5.8");
+            }
 
             Mocker.GetMock<IDiskProvider>()
                   .Setup(v => v.FileExists(It.IsAny<string>()))
@@ -29,10 +28,8 @@ public void SetUp()
             Mocker.GetMock<IDiskProvider>()
                   .Setup(v => v.DeleteFile(It.IsAny<string>()))
                   .Callback<string>(s => File.Delete(s));
-                  
-            Mocker.GetMock<IDiskProvider>()
-                  .Setup(v => v.CanUseGDIPlus())
-                  .Returns(true);
+
+            Mocker.SetConstant<IPlatformInfo>(Mocker.Resolve<PlatformInfo>());
         }
 
         [Test]
@@ -49,9 +46,11 @@ public void should_resize_image()
             fileInfo.Exists.Should().BeTrue();
             fileInfo.Length.Should().BeInRange(1000, 30000);
 
-            var image = System.Drawing.Image.FromFile(resizedFile);
-            image.Height.Should().Be(170);
-            image.Width.Should().Be(170);
+            using (var image = Image.Load(resizedFile))
+            {
+                image.Height.Should().Be(170);
+                image.Width.Should().Be(170);
+            }
         }
 
         [Test]
diff --git a/src/NzbDrone.Core/MediaCover/ImageResizer.cs b/src/NzbDrone.Core/MediaCover/ImageResizer.cs
index 63a202c59..42f64092a 100644
--- a/src/NzbDrone.Core/MediaCover/ImageResizer.cs
+++ b/src/NzbDrone.Core/MediaCover/ImageResizer.cs
@@ -1,6 +1,8 @@
 using System;
 using NzbDrone.Common.Disk;
+using NzbDrone.Common.EnvironmentInfo;
 using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.Formats.Jpeg;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.Memory;
 
@@ -14,23 +16,39 @@ public interface IImageResizer
     public class ImageResizer : IImageResizer
     {
         private readonly IDiskProvider _diskProvider;
+        private readonly bool _enabled;
 
-        public ImageResizer(IDiskProvider diskProvider)
+        public ImageResizer(IDiskProvider diskProvider, IPlatformInfo platformInfo)
         {
             _diskProvider = diskProvider;
 
+            // Random segfaults on mono 5.0 and 5.4
+            if (PlatformInfo.IsMono && platformInfo.Version < new System.Version(5, 8))
+            {
+                return;
+            }
+
+            _enabled = true;
+
             // More conservative memory allocation
             SixLabors.ImageSharp.Configuration.Default.MemoryAllocator = new SimpleGcMemoryAllocator();
+
+            // Thumbnails don't need super high quality
+            SixLabors.ImageSharp.Configuration.Default.ImageFormatsManager.SetEncoder(JpegFormat.Instance, new JpegEncoder
+            {
+                Quality = 92
+            });
         }
 
         public void Resize(string source, string destination, int height)
         {
+            if (!_enabled) return;
+
             try
             {
                 using (var image = Image.Load(source))
                 {
-                    var width = (int)Math.Floor((double)image.Width * (double)height / (double)image.Height);
-                    image.Mutate(x => x.Resize(width, height));
+                    image.Mutate(x => x.Resize(0, height));
                     image.Save(destination);
                 }
             }
diff --git a/src/NzbDrone.Core/MediaCover/MediaCoverService.cs b/src/NzbDrone.Core/MediaCover/MediaCoverService.cs
index 6ce0f1ac6..60ff480d0 100644
--- a/src/NzbDrone.Core/MediaCover/MediaCoverService.cs
+++ b/src/NzbDrone.Core/MediaCover/MediaCoverService.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Net;
+using System.Threading;
 using NLog;
 using NzbDrone.Common.Disk;
 using NzbDrone.Common.EnvironmentInfo;
@@ -40,6 +41,11 @@ public class MediaCoverService :
 
         private readonly string _coverRootFolder;
 
+        // ImageSharp is slow on ARM (no hardware acceleration on mono yet)
+        // So limit the number of concurrent resizing tasks
+        private static SemaphoreSlim _semaphore = new SemaphoreSlim((int)Math.Ceiling(Environment.ProcessorCount / 2.0));
+
+
         public MediaCoverService(IImageResizer resizer,
                                  IHttpClient httpClient,
                                  IDiskProvider diskProvider,
@@ -94,6 +100,8 @@ private string GetMovieCoverPath(int movieId)
 
         private void EnsureCovers(Movie movie, int retried = 0)
         {
+            var toResize = new List<Tuple<MediaCover, bool>>();
+
             foreach (var cover in movie.Images)
             {
                 var fileName = GetCoverPath(movie.Id, cover.CoverType);
@@ -133,7 +141,21 @@ private void EnsureCovers(Movie movie, int retried = 0)
                     _logger.Error(e, "Couldn't download media cover for {0}", movie);
                 }
 
-                EnsureResizedCovers(movie, cover, !alreadyExists);
+                toResize.Add(Tuple.Create(cover, alreadyExists));
+            }
+
+            try
+            {
+                _semaphore.Wait();
+
+                foreach (var tuple in toResize)
+                {
+                    EnsureResizedCovers(movie, tuple.Item1, !tuple.Item2);
+                }
+            }
+            finally
+            {
+                _semaphore.Release();
             }
         }
 
diff --git a/src/NzbDrone.Test.Common/NzbDroneRunner.cs b/src/NzbDrone.Test.Common/NzbDroneRunner.cs
index add19f5f2..c4741c1c0 100644
--- a/src/NzbDrone.Test.Common/NzbDroneRunner.cs
+++ b/src/NzbDrone.Test.Common/NzbDroneRunner.cs
@@ -68,7 +68,7 @@ public void Start()
                     return;
                 }
 
-                Console.WriteLine("Waiting for Radarr to start. Response Status : {0}  [{1}] {2}", statusCall.ResponseStatus, statusCall.StatusDescription, statusCall.ErrorException);
+                Console.WriteLine("Waiting for Radarr to start. Response Status : {0}  [{1}] {2}", statusCall.ResponseStatus, statusCall.StatusDescription, statusCall.ErrorException.Message);
 
                 Thread.Sleep(500);
             }