diff --git a/app/src/main/java/eu/faircode/email/AdapterContact.java b/app/src/main/java/eu/faircode/email/AdapterContact.java
index 96bc0865ed..c2fa5c0250 100644
--- a/app/src/main/java/eu/faircode/email/AdapterContact.java
+++ b/app/src/main/java/eu/faircode/email/AdapterContact.java
@@ -65,6 +65,7 @@ import java.io.InputStream;
 import java.text.NumberFormat;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.ExecutorService;
 
 public class AdapterContact extends RecyclerView.Adapter<AdapterContact.ViewHolder> {
     private Fragment parentFragment;
@@ -84,6 +85,9 @@ public class AdapterContact extends RecyclerView.Adapter<AdapterContact.ViewHold
 
     private NumberFormat NF = NumberFormat.getNumberInstance();
 
+    private static final ExecutorService executor =
+            Helper.getBackgroundExecutor(1, "contacts");
+
     public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {
         private View view;
         private ImageView ivType;
@@ -377,54 +381,69 @@ public class AdapterContact extends RecyclerView.Adapter<AdapterContact.ViewHold
 
         all = contacts;
 
-        List<TupleContactEx> filtered;
-        if (types.size() == 0)
-            filtered = all;
-        else {
-            filtered = new ArrayList<>();
-            for (TupleContactEx contact : all)
-                if (types.contains(contact.type))
-                    filtered.add(contact);
-        }
-
-        List<TupleContactEx> items;
-        if (TextUtils.isEmpty(search))
-            items = filtered;
-        else {
-            items = new ArrayList<>();
-            String query = search.toLowerCase().trim();
-            for (TupleContactEx contact : filtered)
-                if (contact.email.toLowerCase().contains(query) ||
-                        (contact.name != null && contact.name.toLowerCase().contains(query)))
-                    items.add(contact);
-        }
-
-        DiffUtil.DiffResult diff = DiffUtil.calculateDiff(new DiffCallback(selected, items), false);
+        new SimpleTask<List<TupleContactEx>>() {
+            @Override
+            protected List<TupleContactEx> onExecute(Context context, Bundle args) throws Throwable {
+                List<TupleContactEx> filtered;
+                if (types.size() == 0)
+                    filtered = contacts;
+                else {
+                    filtered = new ArrayList<>();
+                    for (TupleContactEx contact : contacts)
+                        if (types.contains(contact.type))
+                            filtered.add(contact);
+                }
 
-        selected = items;
+                List<TupleContactEx> items;
+                if (TextUtils.isEmpty(search))
+                    items = filtered;
+                else {
+                    items = new ArrayList<>();
+                    String query = search.toLowerCase().trim();
+                    for (TupleContactEx contact : filtered)
+                        if (contact.email.toLowerCase().contains(query) ||
+                                (contact.name != null && contact.name.toLowerCase().contains(query)))
+                            items.add(contact);
+                }
 
-        diff.dispatchUpdatesTo(new ListUpdateCallback() {
-            @Override
-            public void onInserted(int position, int count) {
-                Log.d("Inserted @" + position + " #" + count);
+                return items;
             }
 
             @Override
-            public void onRemoved(int position, int count) {
-                Log.d("Removed @" + position + " #" + count);
-            }
+            protected void onExecuted(Bundle args, List<TupleContactEx> items) {
+                DiffUtil.DiffResult diff = DiffUtil.calculateDiff(new DiffCallback(selected, items), false);
 
-            @Override
-            public void onMoved(int fromPosition, int toPosition) {
-                Log.d("Moved " + fromPosition + ">" + toPosition);
+                selected = items;
+
+                diff.dispatchUpdatesTo(new ListUpdateCallback() {
+                    @Override
+                    public void onInserted(int position, int count) {
+                        Log.d("Inserted @" + position + " #" + count);
+                    }
+
+                    @Override
+                    public void onRemoved(int position, int count) {
+                        Log.d("Removed @" + position + " #" + count);
+                    }
+
+                    @Override
+                    public void onMoved(int fromPosition, int toPosition) {
+                        Log.d("Moved " + fromPosition + ">" + toPosition);
+                    }
+
+                    @Override
+                    public void onChanged(int position, int count, Object payload) {
+                        Log.d("Changed @" + position + " #" + count);
+                    }
+                });
+                diff.dispatchUpdatesTo(AdapterContact.this);
             }
 
             @Override
-            public void onChanged(int position, int count, Object payload) {
-                Log.d("Changed @" + position + " #" + count);
+            protected void onException(Bundle args, Throwable ex) {
+                Log.unexpectedError(parentFragment.getParentFragmentManager(), ex);
             }
-        });
-        diff.dispatchUpdatesTo(this);
+        }.setExecutor(executor).execute(context, owner, new Bundle(), "contacts:filter");
     }
 
     public void search(String query) {