un coup d'oeil is already rapid, no ?

Earl,

 ‘ un coup d’œil ’ is a noun expression - in some contexts, equivalent to ‘ a quick look ‘ or ‘ a glance’ in English. 

‘ Un coup d’œil rapide ‘ is also a noun expression with ‘ rapide ‘ as an emphasiser, just as we might say ‘ a really quick look ‘ or ‘ a quick glance ‘ in English.

 https://www.wordreference.com/fren/coup%2520d%2527%C5%93il