diff --git a/GitUI/Avatars/AvatarDownloader.cs b/GitUI/Avatars/AvatarDownloader.cs
index 72271a9d86f..9ebd47a1fe8 100644
--- a/GitUI/Avatars/AvatarDownloader.cs
+++ b/GitUI/Avatars/AvatarDownloader.cs
@@ -6,13 +6,17 @@
 using System.Security.Cryptography;
 using System.Text;
 using System.Text.RegularExpressions;
+using System.Threading;
 using System.Threading.Tasks;
 using GitCommands;
+using Microsoft.VisualStudio.Threading;
 
 namespace GitUI.Avatars
 {
     public sealed class AvatarDownloader : IAvatarProvider
     {
+        private const int MaxConcurrentDownloads = 10;
+
         /* A brief skim through the GitExtensions repo history shows GitHub emails with the following user names:
          *
          * 25421792+mserfli
@@ -25,6 +29,8 @@ public sealed class AvatarDownloader : IAvatarProvider
          */
         private static readonly Regex _gitHubEmailRegex = new Regex(@"^(\d+\+)?(?<username>[^@]+)@users\.noreply\.github\.com$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
+        private static readonly SemaphoreSlim _downloadSemaphore = new SemaphoreSlim(initialCount: MaxConcurrentDownloads);
+
         private static readonly ConcurrentDictionary<Uri, (DateTime, Task<Image>)> _downloads = new ConcurrentDictionary<Uri, (DateTime, Task<Image>)>();
 
         /// <inheritdoc />
@@ -146,6 +152,15 @@ async Task<Image> DownloadImageAsync(Uri imageUrl)
 
                 async Task<Image> Download()
                 {
+                    // WebClient.OpenReadTaskAsync can block before returning a task, so make sure we
+                    // make such calls on the thread pool, and limit the number of concurrent requests.
+
+                    // Get onto background thread
+                    await TaskScheduler.Default;
+
+                    // Limit the number of concurrent download requests
+                    await _downloadSemaphore.WaitAsync();
+
                     try
                     {
                         using (var webClient = new WebClient { Proxy = WebRequest.DefaultWebProxy })
@@ -163,6 +178,10 @@ async Task<Image> Download()
                         // catch IO errors
                         Trace.WriteLine(ex.Message);
                     }
+                    finally
+                    {
+                        _downloadSemaphore.Release();
+                    }
 
                     return null;
                 }
diff --git a/GitUI/UserControls/AvatarControl.cs b/GitUI/UserControls/AvatarControl.cs
index 142cd052855..9b7ed0d4568 100644
--- a/GitUI/UserControls/AvatarControl.cs
+++ b/GitUI/UserControls/AvatarControl.cs
@@ -104,6 +104,8 @@ private async Task UpdateAvatarAsync()
 
             if (!token.IsCancellationRequested)
             {
+                await this.SwitchToMainThreadAsync();
+
                 RefreshImage(image);
             }
         }
diff --git a/Plugins/Gource/GourceStart.cs b/Plugins/Gource/GourceStart.cs
index b71478b4809..96be05222d0 100644
--- a/Plugins/Gource/GourceStart.cs
+++ b/Plugins/Gource/GourceStart.cs
@@ -73,6 +73,9 @@ private void Button1Click(object sender, EventArgs e)
                     GitWorkingDir = WorkingDir.Text;
 
                     RunRealCmdDetached(GourcePath.Text, arguments);
+
+                    await this.SwitchToMainThreadAsync();
+
                     Close();
                 });
         }