diff --git a/core/src/main/java/hudson/model/AbstractBuild.java b/core/src/main/java/hudson/model/AbstractBuild.java
index 2d1bc35d4e3081ee1190075ccb8f7cd419dd1fbf..72ea53596cfa7228a67da625f98f6d53966d5a40 100644
--- a/core/src/main/java/hudson/model/AbstractBuild.java
+++ b/core/src/main/java/hudson/model/AbstractBuild.java
@@ -62,6 +62,7 @@ import hudson.util.Iterators;
 import hudson.util.LogTaskListener;
 import hudson.util.VariableResolver;
 import jenkins.model.Jenkins;
+import jenkins.model.lazy.AbstractLazyLoadRunMap.Direction;
 import org.kohsuke.stapler.Stapler;
 import org.kohsuke.stapler.StaplerRequest;
 import org.kohsuke.stapler.StaplerResponse;
@@ -170,6 +171,26 @@ public abstract class AbstractBuild<P extends AbstractProject<P,R>,R extends Abs
         return getParent();
     }
 
+    private boolean previousBuildComputed, nextBuildComputed;
+
+    @Override
+    public R getPreviousBuild() {
+        if (previousBuild==null && !previousBuildComputed) {
+            previousBuild = getParent().builds.search(number-1, Direction.DESC);
+            previousBuildComputed = true;
+        }
+        return previousBuild;
+    }
+
+    @Override
+    public R getNextBuild() {
+        if (nextBuild==null && !nextBuildComputed) {
+            nextBuild = getParent().builds.search(number+1, Direction.ASC);
+            nextBuildComputed = true;
+        }
+        return nextBuild;
+    }
+
     /**
      * Returns a {@link Slave} on which this build was done.
      *
diff --git a/core/src/main/java/hudson/model/AbstractProject.java b/core/src/main/java/hudson/model/AbstractProject.java
index 046e3fc7bf02440675134cf75783d24a470fa693..aa039688f83c5d8e30996ab302437dddca9be90d 100644
--- a/core/src/main/java/hudson/model/AbstractProject.java
+++ b/core/src/main/java/hudson/model/AbstractProject.java
@@ -160,7 +160,7 @@ public abstract class AbstractProject<P extends AbstractProject<P,R>,R extends A
      * {@link Run#getPreviousBuild()}
      */
     @Restricted(NoExternalUse.class)
-    protected transient /*almost final*/ RunMap<R> builds = new RunMap<R>();
+    protected transient RunMap<R> builds = new RunMap<R>();
 
     /**
      * The quiet period. Null to delegate to the system default.
@@ -269,9 +269,7 @@ public abstract class AbstractProject<P extends AbstractProject<P,R>,R extends A
     public void onLoad(ItemGroup<? extends Item> parent, String name) throws IOException {
         super.onLoad(parent, name);
 
-        if (this.builds==null)
-            this.builds = new RunMap<R>();
-        this.builds.load(this,new Constructor<R>() {
+        this.builds = new RunMap<R>(getBuildDir(),new Constructor<R>() {
             public R create(File dir) throws IOException {
                 return loadBuild(dir);
             }
diff --git a/core/src/main/java/hudson/model/Run.java b/core/src/main/java/hudson/model/Run.java
index eb44e7c2f416ca0dd16c6c46b8670f96b7f6a44b..9c17f985182f64ce4218a577bf2509b6b9e53451 100644
--- a/core/src/main/java/hudson/model/Run.java
+++ b/core/src/main/java/hudson/model/Run.java
@@ -44,7 +44,6 @@ import hudson.model.Descriptor.FormException;
 import hudson.model.listeners.RunListener;
 import hudson.model.listeners.SaveableListener;
 import hudson.security.PermissionScope;
-import jenkins.model.Jenkins.MasterComputer;
 import hudson.search.SearchIndexBuilder;
 import hudson.security.ACL;
 import hudson.security.AccessControlled;
@@ -640,10 +639,11 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
         // a new build is in progress
         BallColor baseColor;
-        if(previousBuild==null)
+        RunT pb = getPreviousBuild();
+        if(pb==null)
             baseColor = BallColor.GREY;
         else
-            baseColor = previousBuild.getIconColor();
+            baseColor = pb.getIconColor();
 
         return baseColor.anime();
     }
@@ -747,10 +747,10 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Returns the last build that was actually built - i.e., skipping any with Result.NOT_BUILT
      */
     public RunT getPreviousBuiltBuild() {
-        RunT r=previousBuild;
+        RunT r=getPreviousBuild();
         // in certain situations (aborted m2 builds) r.getResult() can still be null, although it should theoretically never happen
         while( r!=null && (r.getResult() == null || r.getResult()==Result.NOT_BUILT) )
-            r=r.previousBuild;
+            r=r.getPreviousBuild();
         return r;
     }
 
@@ -758,9 +758,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Returns the last build that didn't fail before this build.
      */
     public RunT getPreviousNotFailedBuild() {
-        RunT r=previousBuild;
+        RunT r=getPreviousBuild();
         while( r!=null && r.getResult()==Result.FAILURE )
-            r=r.previousBuild;
+            r=r.getPreviousBuild();
         return r;
     }
 
@@ -768,9 +768,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * Returns the last failed build before this build.
      */
     public RunT getPreviousFailedBuild() {
-        RunT r=previousBuild;
+        RunT r=getPreviousBuild();
         while( r!=null && r.getResult()!=Result.FAILURE )
-            r=r.previousBuild;
+            r=r.getPreviousBuild();
         return r;
     }
 
@@ -779,9 +779,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
      * @since 1.383
      */
     public RunT getPreviousSuccessfulBuild() {
-        RunT r=previousBuild;
+        RunT r=getPreviousBuild();
         while( r!=null && r.getResult()!=Result.SUCCESS )
-            r=r.previousBuild;
+            r=r.getPreviousBuild();
         return r;
     }
 
diff --git a/core/src/main/java/hudson/model/RunMap.java b/core/src/main/java/hudson/model/RunMap.java
index 6b962b00f020b654b1d218b6eb77f719c3e7ed1c..edf5864f5d9aaf11829605f8caae206112cdbd31 100644
--- a/core/src/main/java/hudson/model/RunMap.java
+++ b/core/src/main/java/hudson/model/RunMap.java
@@ -62,10 +62,23 @@ public final class RunMap<R extends Run<?,R>> extends AbstractLazyLoadRunMap<R>
     // patch up next/previous build link
 
 
+    /**
+     * @deprecated
+     *      Use {@link #RunMap(File, Constructor)}.
+     */
     public RunMap() {
         super(null); // will be set later
     }
 
+    /**
+     * @param cons
+     *      Used to create new instance of {@link Run}.
+     */
+    public RunMap(File baseDir, Constructor cons) {
+        super(baseDir);
+        this.cons = cons;
+    }
+
     @Override
     public boolean remove(R run) {
         if(run.nextBuild!=null)
@@ -179,8 +192,10 @@ public final class RunMap<R extends Run<?,R>> extends AbstractLazyLoadRunMap<R>
      *      Job that owns this map.
      * @param cons
      *      Used to create new instance of {@link Run}.
+     * @deprecated
+     *      Use {@link #RunMap(File, Constructor)}
      */
-    public synchronized void load(Job job, Constructor<R> cons) {
+    public void load(Job job, Constructor<R> cons) {
         this.cons = cons;
         initBaseDir(job.getBuildDir());
     }
diff --git a/core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java b/core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java
index ae185c0b99c7e94e7c1ebede18410adf805df1d1..fff288b27c156e5981e9af291f737c6941715335 100644
--- a/core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java
+++ b/core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java
@@ -94,7 +94,6 @@ public abstract class AbstractLazyLoadRunMap<R> extends AbstractMap<Integer,R> i
      */
     private File dir;
 
-    @Restricted(NoExternalUse.class) // for now
     protected AbstractLazyLoadRunMap(File dir) {
         this.dir = dir;
         initBaseDir(dir);