use sampleImage() on GIFs as it is much faster

inc/image.php

@@ -187,7 +187,8 @@
 					
 					//if($i < $config['thumb_keep_animation_frames']) {
 					if(in_array($i, $keep_frames)) {
-						$frame->scaleImage($this->width, $this->height, false);
+						// $frame->scaleImage($this->width, $this->height, false);
+						$frame->sampleImage($this->width, $this->height);
 						$frame->setImagePage($this->width, $this->height, 0, 0);
 						$frame->setImageDelay($delay);
 						$delay = 0;