What about something like this: 

```scala
private val dateFormatTemplate = {
   val df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'") //use ISO_8601 format
   df.setLenient(false)
   df.setTimeZone(TimeZone.getTimeZone("UTC"))
   df
}
def dateFormat = dateFormatTemplate.clone.asInstanceOf[SimpleDateFormat]
```

Cloning is about 20-30x faster then creating a new SimpleDateFormat by parsing the format-pattern again and again.