diff --git a/src/IDF/Scm.php b/src/IDF/Scm.php
index c104651..9e8de2d 100644
--- a/src/IDF/Scm.php
+++ b/src/IDF/Scm.php
@@ -40,5 +40,43 @@ class IDF_Scm
         return call_user_func(array($scms[$scm], 'factory'),
                               $request->project);
     }
+
+    /**
+     * Equivalent to exec but with caching.
+     *
+     * @param string Command
+     * @param &array Output
+     * @param &int Return value
+     * @return string Last line of the output
+     */
+    public static function exec($command, &$output=array(), &$return=0)
+    {
+        $key = md5($command);
+        $cache = Pluf_Cache::factory();
+        if (null === ($res=$cache->get($key))) {
+            $ll = exec($command, $output, $return);
+            $cache->set($key, array($ll, $return, $output));
+        } else {
+            list($ll, $return, $output) = $res;
+        }
+        return $ll;
+    }
+
+    /**
+     * Equivalent to shell_exec but with caching.
+     *
+     * @param string Command
+     * @return string Output of the command
+     */
+    public static function shell_exec($command)
+    {
+        $key = md5($command);
+        $cache = Pluf_Cache::factory();
+        if (null === ($res=$cache->get($key))) {
+            $res = shell_exec($command);
+            $cache->set($key, $res);
+        } 
+        return $res;
+    }
 }
 
diff --git a/src/IDF/Scm/Git.php b/src/IDF/Scm/Git.php
index f072a71..23870fb 100644
--- a/src/IDF/Scm/Git.php
+++ b/src/IDF/Scm/Git.php
@@ -78,7 +78,7 @@ class IDF_Scm_Git
                        escapeshellarg($this->repo),
                        escapeshellarg($hash));
         $ret = 0; $out = array();
-        exec($cmd, &$out, &$ret);
+        IDF_Scm::exec($cmd, &$out, &$ret);
         if ($ret != 0) return false;
         return trim($out[0]);
     }
@@ -121,7 +121,7 @@ class IDF_Scm_Git
         $rawlog = array();
         $cmd = sprintf('GIT_DIR=%s git log --raw --abbrev=40 --pretty=oneline %s',
                        escapeshellarg($this->repo), escapeshellarg($commit));
-        exec($cmd, &$rawlog);
+        IDF_Scm::exec($cmd, &$rawlog);
         // We reverse the log to be able to use a fixed efficient
         // regex without back tracking.
         $rawlog = implode("\n", array_reverse($rawlog));
@@ -165,7 +165,7 @@ class IDF_Scm_Git
                        escapeshellarg($tree));
         $out = array();
         $res = array();
-        exec($cmd, &$out);
+        IDF_Scm::exec($cmd, &$out);
         foreach ($out as $line) {
             list($perm, $type, $hash, $size, $file) = preg_split('/ |\t/', $line, 5, PREG_SPLIT_NO_EMPTY);
             $res[] = (object) array('perm' => $perm, 'type' => $type, 
@@ -190,7 +190,7 @@ class IDF_Scm_Git
                        escapeshellarg($this->repo), 
                        escapeshellarg($commit));
         $out = array();
-        exec($cmd, &$out);
+        IDF_Scm::exec($cmd, &$out);
         foreach ($out as $line) {
             list($perm, $type, $hash, $size, $file) = preg_split('/ |\t/', $line, 5, PREG_SPLIT_NO_EMPTY);
             if ($totest == $file) {
@@ -211,9 +211,9 @@ class IDF_Scm_Git
      */
     public function getBlob($request_file_info, $dummy=null)
     {
-        return shell_exec(sprintf('GIT_DIR=%s git-cat-file blob %s',
-                                  escapeshellarg($this->repo), 
-                                  escapeshellarg($request_file_info->hash)));
+        return IDF_Scm::shell_exec(sprintf('GIT_DIR=%s git-cat-file blob %s',
+                                    escapeshellarg($this->repo), 
+                                    escapeshellarg($request_file_info->hash)));
     }
 
     /**
@@ -224,8 +224,8 @@ class IDF_Scm_Git
     public function getBranches()
     {
         $out = array();
-        exec(sprintf('GIT_DIR=%s git branch', 
-                     escapeshellarg($this->repo)), &$out);
+        IDF_Scm::exec(sprintf('GIT_DIR=%s git branch', 
+                              escapeshellarg($this->repo)), &$out);
         $res = array();
         foreach ($out as $b) {
             $res[] = substr($b, 2);
@@ -246,7 +246,7 @@ class IDF_Scm_Git
                        "'".$this->mediumtree_fmt."'", 
                        escapeshellarg($commit));
         $out = array();
-        exec($cmd, &$out);
+        IDF_Scm::exec($cmd, &$out);
         $log = array();
         $change = array();
         $inchange = false;
@@ -281,7 +281,7 @@ class IDF_Scm_Git
                        escapeshellarg($this->repo), $n, $this->mediumtree_fmt, 
                        escapeshellarg($commit));
         $out = array();
-        exec($cmd, &$out);
+        IDF_Scm::exec($cmd, &$out);
         return self::parseLog($out, 4);
     }
 
diff --git a/src/IDF/Scm/Svn.php b/src/IDF/Scm/Svn.php
index 0b5f561..3cd19fd 100644
--- a/src/IDF/Scm/Svn.php
+++ b/src/IDF/Scm/Svn.php
@@ -104,7 +104,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo.'/'.$path),
                        escapeshellarg($rev));
-        $xmlInfo = shell_exec($cmd);
+        $xmlInfo = IDF_Scm::shell_exec($cmd);
 
         // If exception is thrown, return false
         try {
@@ -142,7 +142,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo.'/'.$folder),
                        escapeshellarg($rev));
-        $xmlLs = shell_exec($cmd);
+        $xmlLs = IDF_Scm::shell_exec($cmd);
         $xml = simplexml_load_string($xmlLs);
         $res = array();
         foreach ($xml->list->entry as $entry) {
@@ -185,7 +185,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($file),
                        escapeshellarg($rev));
-        $xmlLog = shell_exec($cmd);
+        $xmlLog = IDF_Scm::shell_exec($cmd);
         $xml = simplexml_load_string($xmlLog);
         return (string) $xml->logentry->msg;
     }
@@ -205,7 +205,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo.'/'.$totest),
                        escapeshellarg($rev));
-        $xmlInfo = shell_exec($cmd);
+        $xmlInfo = IDF_Scm::shell_exec($cmd);
         $xml = simplexml_load_string($xmlInfo);
         $entry = $xml->entry;
 
@@ -237,7 +237,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo.'/'.$request_file_info->fullpath),
                        escapeshellarg($rev));
-        return shell_exec($cmd);
+        return IDF_Scm::shell_exec($cmd);
     }
 
 
@@ -267,7 +267,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo),
                        escapeshellarg($rev));
-        $xmlRes = shell_exec($cmd);
+        $xmlRes = IDF_Scm::shell_exec($cmd);
         $xml = simplexml_load_string($xmlRes);
 
         $res['author'] = (string) $xml->logentry->author;
@@ -289,7 +289,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->username),
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo));
-        return shell_exec($cmd);
+        return IDF_Scm::shell_exec($cmd);
     }
 
 
@@ -310,7 +310,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo),
                        escapeshellarg($rev));
-        $xmlRes = shell_exec($cmd);
+        $xmlRes = IDF_Scm::shell_exec($cmd);
         $xml = simplexml_load_string($xmlRes);
 
         $res = array();
@@ -358,7 +358,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo.'/'.$path),
                        escapeshellarg($rev));
-        $xmlProps = shell_exec($cmd);
+        $xmlProps = IDF_Scm::shell_exec($cmd);
         $props = simplexml_load_string($xmlProps);
 
         // No properties, returns an empty array
@@ -393,7 +393,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo.'/'.$path),
                        escapeshellarg($rev));
-        $xmlProp = shell_exec($cmd);
+        $xmlProp = IDF_Scm::shell_exec($cmd);
         $prop = simplexml_load_string($xmlProp);
 
         return (string) $prop->target->property;
@@ -415,7 +415,7 @@ class IDF_Scm_Svn
                        escapeshellarg($this->password),
                        escapeshellarg($this->repo),
                        escapeshellarg($rev));
-        $xmlInfo = shell_exec($cmd);
+        $xmlInfo = IDF_Scm::shell_exec($cmd);
 
         $xml = simplexml_load_string($xmlInfo);
         return (string) $xml->entry->commit['revision'];