I've just had a different thought. Those areas on the body suit are not really showing true reflections, but only specular reflections. In other words, they are only reflecting diffuse light, and not objects in the scene.

You would therefore do better to use a Specular node (or Blinn) instead of reflection, and it would render much faster.

You would still need to use the map to control the reflective areas, but you would plug it into the Specular Value and not the Reflection Value.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)