diff --git a/src/xsprintf/PhutilQueryString.php b/src/xsprintf/PhutilQueryString.php
--- a/src/xsprintf/PhutilQueryString.php
+++ b/src/xsprintf/PhutilQueryString.php
@@ -4,6 +4,7 @@
 
   private $maskedString;
   private $unmaskedString;
+  private $isMasked;
 
   public function __construct(PhutilQsprintfInterface $escaper, array $argv) {
     // Immediately render the query into a static scalar value.
@@ -30,13 +31,63 @@
       ),
       $argv);
 
-    $unmasked_string = xsprintf(
-      'xsprintf_query',
-      array(
-        'escaper' => $escaper,
-        'unmasked' => true,
-      ),
-      $argv);
+    // As an optimization, only render the unmasked string if it may differ
+    // from the masked string. The strings may differ if any argument is a
+    // "PhutilOpaqueEnvelope", or if any argument is a "PhutilQueryString"
+    // with different masked and unmasked values.
+
+    // We always render the masked string and only render the unmasked string
+    // if we believe we need it, so a mistake here will cause us to incorrectly
+    // execute a query with "********" in it, not incorrectly disclose
+    // sensitive query parameters.
+
+    $need_unmasked = false;
+    foreach ($argv as $arg) {
+      if ($arg instanceof PhutilQueryString) {
+        if ($arg->isMasked) {
+          $need_unmasked = true;
+          break;
+        }
+        continue;
+      }
+
+      if ($arg instanceof PhutilOpaqueEnvelope) {
+        $need_unmasked = true;
+        break;
+      }
+
+      if (is_array($arg)) {
+        foreach ($arg as $item) {
+          if ($item instanceof PhutilQueryString) {
+            if ($item->isMasked) {
+              $need_unmasked = true;
+              break;
+            }
+            continue;
+          }
+
+          // If we find an array item which is not a "PhutilQueryString", we
+          // know this argument can not require us to unmask the string, since
+          // no valid argument to "qsprintf(...)" may be a list with a mixture
+          // of query strings and other values.
+          break;
+        }
+      }
+    }
+
+    if ($need_unmasked) {
+      $unmasked_string = xsprintf(
+        'xsprintf_query',
+        array(
+          'escaper' => $escaper,
+          'unmasked' => true,
+        ),
+        $argv);
+      $this->isMasked = true;
+    } else {
+      $unmasked_string = $masked_string;
+      $this->isMasked = false;
+    }
 
     $this->maskedString = $masked_string;
     $this->unmaskedString = $unmasked_string;