diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java b/gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java
index 823ab0f11e..aa2f9de338 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java
@@ -558,7 +558,7 @@ public class MergeOp implements AutoCloseable {
       checkState(cs.ids().contains(change.getId()),
           "change %s missing from %s", change.getId(), cs);
       this.commits = new CommitStatus(cs);
-      reloadChanges(cs);
+      MergeSuperSet.reloadChanges(cs);
       logDebug("Calculated to merge {}", cs);
       if (checkSubmitRules) {
         logDebug("Checking submit rules and state");
@@ -580,13 +580,6 @@ public class MergeOp implements AutoCloseable {
     }
   }
 
-  private static void reloadChanges(ChangeSet cs) throws OrmException {
-    // Reload changes in case index was stale.
-    for (ChangeData cd : cs.changes()) {
-      cd.reloadChange();
-    }
-  }
-
   private void failFast(ChangeSet cs) throws ResourceConflictException {
     if (commits.isOk()) {
       return;
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/git/MergeSuperSet.java b/gerrit-server/src/main/java/com/google/gerrit/server/git/MergeSuperSet.java
index b3538b7280..8fa766beee 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/git/MergeSuperSet.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/git/MergeSuperSet.java
@@ -15,6 +15,7 @@
 package com.google.gerrit.server.git;
 
 import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Multimap;
 import com.google.gerrit.common.data.SubmitTypeRecord;
 import com.google.gerrit.extensions.client.SubmitType;
@@ -25,6 +26,7 @@ import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.change.Submit;
 import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.index.ChangeField;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gerrit.server.query.change.InternalChangeQuery;
 import com.google.gwtorm.server.OrmException;
@@ -64,6 +66,14 @@ import java.util.Set;
 public class MergeSuperSet {
   private static final Logger log = LoggerFactory.getLogger(MergeOp.class);
 
+  public static void reloadChanges(ChangeSet cs) throws OrmException {
+    // Clear exactly the fields requested by query() below.
+    for (ChangeData cd : cs.changes()) {
+      cd.reloadChange();
+      cd.setPatchSets(null);
+    }
+  }
+
   private final ChangeData.Factory changeDataFactory;
   private final Provider<InternalChangeQuery> queryProvider;
   private final GitRepositoryManager repoManager;
@@ -144,7 +154,7 @@ public class MergeSuperSet {
           }
 
           if (!hashes.isEmpty()) {
-            Iterable<ChangeData> destChanges = queryProvider.get()
+            Iterable<ChangeData> destChanges = query()
                 .byCommitsOnBranchNotMerged(
                   repo, db, cd.change().getDest(), hashes);
             for (ChangeData chd : destChanges) {
@@ -171,7 +181,7 @@ public class MergeSuperSet {
         chgs.add(cd);
         String topic = cd.change().getTopic();
         if (!Strings.isNullOrEmpty(topic) && !topicsTraversed.contains(topic)) {
-          chgs.addAll(queryProvider.get().byTopicOpen(topic));
+          chgs.addAll(query().byTopicOpen(topic));
           done = false;
           topicsTraversed.add(topic);
         }
@@ -182,6 +192,17 @@ public class MergeSuperSet {
     return newCs;
   }
 
+  private InternalChangeQuery query() {
+    // Request fields required for completing the ChangeSet without having to
+    // touch the database. This provides reasonable performance when loading the
+    // change screen; callers that care about reading the latest value of these
+    // fields should clear them explicitly using reloadChanges().
+    Set<String> fields = ImmutableSet.of(
+        ChangeField.CHANGE.getName(),
+        ChangeField.PATCH_SET.getName());
+    return queryProvider.get().setRequestedFields(fields);
+  }
+
   private void logError(String msg) {
     if (log.isErrorEnabled()) {
       log.error(msg);