[geary/cherry-pick-940241bb] Merge branch 'improve-conversation-loading-performance' into 'mainline'

[Michael Gratton <mjog src gnome org>]

commit 0819fd1ad42ecd511b49cbbbda9e109dbe762673
Author: Michael Gratton <mike vee net>
Date:   Mon Apr 8 00:11:43 2019 +0000

    Merge branch 'improve-conversation-loading-performance' into 'mainline'
    
    Improve conversation loading performance
    
    See merge request GNOME/geary!181
    
    (cherry picked from commit 940241bbe1f368d0b130c23655a74698f8837c4d)
    
    ca399921 conversation: update GUI every 10 mails

 src/client/conversation-viewer/conversation-list-box.vala | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/src/client/conversation-viewer/conversation-list-box.vala 
b/src/client/conversation-viewer/conversation-list-box.vala
index a4250f39..3747bc87 100644
--- a/src/client/conversation-viewer/conversation-list-box.vala
+++ b/src/client/conversation-viewer/conversation-list-box.vala
@@ -816,6 +816,7 @@ public class ConversationListBox : Gtk.ListBox, Geary.BaseInterface {
         // but keep the scrollbar adjusted so that the first
         // interesting message remains visible.
         Gtk.Adjustment listbox_adj = get_adjustment();
+        int i_mail_loaded = 0;
         foreach (Geary.Email email in to_insert) {
             EmailRow row = add_email(email, false);
             // Since uninteresting rows are inserted above the
@@ -831,7 +832,9 @@ public class ConversationListBox : Gtk.ListBox, Geary.BaseInterface {
             loading_height = 0;
 
             yield row.view.load_avatar(this.avatar_store);
-            yield throttle_loading();
+            if (i_mail_loaded % 10 == 0)
+                yield throttle_loading();
+            ++i_mail_loaded;
         }
 
         set_sort_func(on_sort);