some micro-optimizations made

refs issue #3657

src/Composer/IO/ConsoleIO.php

@@ -96,16 +96,11 @@ class ConsoleIO extends BaseIO
     public function write($messages, $newline = true)
     {
         if (null !== $this->startTime) {
-            $messages = (array) $messages;
-            $startTime = $this->startTime;
-            $messages = array_map(function ($message) use ($startTime) {
-                return sprintf(
-                    '[%.1fMB/%.2fs] %s',
-                    memory_get_usage() / 1024 / 1024,
-                    microtime(true) - $startTime,
-                    $message
-                );
-            }, $messages);
+            $memoryUsage = memory_get_usage() / 1024 / 1024;
+            $timeSpent = microtime(true) - $this->startTime;
+            $messages = array_map(function ($message) use ($memoryUsage, $timeSpent) {
+                return sprintf('[%.1fMB/%.2fs] %s', $memoryUsage, $timeSpent, $message);
+            }, (array) $messages);
         }
         $this->output->write($messages, $newline);
         $this->lastMessage = join($newline ? "\n" : '', (array) $messages);