diff --git a/src/IDF/Scm/Git.php b/src/IDF/Scm/Git.php
index ebe0530..3ddaf5b 100644
--- a/src/IDF/Scm/Git.php
+++ b/src/IDF/Scm/Git.php
@@ -286,6 +286,39 @@ class IDF_Scm_Git
         return $out[0];
     }
 
+    /**
+     * Get commit size.
+     *
+     * Get the sum of all the added/removed lines and the number of
+     * affected files.
+     *
+     * @param string Commit ('HEAD')
+     * @return array array(added, removed, affected)
+     */
+    public function getCommitSize($commit='HEAD')
+    {
+        $cmd = sprintf('GIT_DIR=%s git log --numstat -1 --pretty=format:%s %s',
+                       escapeshellarg($this->repo), 
+                       "'commit %H%n'", 
+                       escapeshellarg($commit));
+        $out = array();
+        IDF_Scm::exec($cmd, $out);
+        $affected = count($out) - 2;
+        $added = 0;
+        $removed = 0;
+        $c=0;
+        foreach ($out as $line) {
+            $c++;
+            if ($c < 3) {
+                continue;
+            }
+            list($a, $r, $f) = preg_split("/[\s]+/", $line, 3, PREG_SPLIT_NO_EMPTY);
+            $added+=$a;
+            $removed+=$r;
+        }
+        return array($added, $removed, $affected);
+    }
+
     /**
      * Get latest changes.
      *
diff --git a/src/IDF/Scm/Mercurial.php b/src/IDF/Scm/Mercurial.php
index 24b0cf1..499f2ee 100644
--- a/src/IDF/Scm/Mercurial.php
+++ b/src/IDF/Scm/Mercurial.php
@@ -302,6 +302,19 @@ class IDF_Scm_Mercurial
         return $out[0];
     }
 
+    /**
+     * Get commit size.
+     *
+     * Get the sum of all the added/removed lines and the number of
+     * affected files.
+     *
+     * @param string Commit ('HEAD')
+     * @return array array(added, removed, affected)
+     */
+    public function getCommitSize($commit='HEAD')
+    {
+        return array(0, 0, 0);
+    }
 
     /**
      * Get latest changes.
diff --git a/src/IDF/Scm/Svn.php b/src/IDF/Scm/Svn.php
index 677e81a..02ee6a4 100644
--- a/src/IDF/Scm/Svn.php
+++ b/src/IDF/Scm/Svn.php
@@ -291,6 +291,20 @@ class IDF_Scm_Svn
         return (object) $res;
     }
 
+    /**
+     * Get commit size.
+     *
+     * Get the sum of all the added/removed lines and the number of
+     * affected files.
+     *
+     * @param string Commit ('HEAD')
+     * @return array array(added, removed, affected)
+     */
+    public function getCommitSize($commit='HEAD')
+    {
+        return array(0, 0, 0);
+    }
+
     private function getDiff($rev='HEAD')
     {
         $res = array();
diff --git a/src/IDF/Views/Source.php b/src/IDF/Views/Source.php
index e5b4f1b..b2c9d92 100644
--- a/src/IDF/Views/Source.php
+++ b/src/IDF/Views/Source.php
@@ -216,7 +216,9 @@ class IDF_Views_Source
         }
         $title = sprintf(__('%s Commit Details'), (string) $request->project);
         $page_title = sprintf(__('%s Commit Details - %s'), (string) $request->project, $commit);
-        $cobject = $scm->getCommit($commit, true);
+        $size = $scm->getCommitSize($commit);
+        $large = ($size[2] > 100 or ($size[0] + $size[1]) > 20000);
+        $cobject = $scm->getCommit($commit, !$large);
         $rcommit = IDF_Commit::getOrAdd($cobject, $request->project);
         $diff = new IDF_Diff($cobject->changes);
         $diff->parse();
@@ -231,6 +233,7 @@ class IDF_Views_Source
                                                      'branches' => $branches,
                                                      'scm' => $scmConf,
                                                      'rcommit' => $rcommit,
+                                                     'large_commit' => $large,
                                                      ),
                                                $request);
     }
diff --git a/src/IDF/templates/idf/source/commit.html b/src/IDF/templates/idf/source/commit.html
index 5e40c03..6e0eb6b 100644
--- a/src/IDF/templates/idf/source/commit.html
+++ b/src/IDF/templates/idf/source/commit.html
@@ -31,10 +31,11 @@
 <h2>{trans 'Change Details'}</h2>
 
 {$diff.as_html()}
+{/if}{if count($diff.files) or $large_commit}
 {aurl 'url', 'IDF_Views_Source::downloadDiff', array($project.shortname, $commit)}
 <p class="right soft"><a href="{$url}"><img style="vertical-align: text-bottom;" src="{media '/idf/img/package-grey.png'}" alt="{trans 'Archive'}" align="bottom" /></a> <a href="{$url}">{trans 'Download the corresponding diff file'}</a></p>
-
 {/if}
+
 {/block}
 {block context}
 {if $scm == 'git'}