README: Add performance notes.
README: Add performance notes.

sahilshah/openface,francisleunggie/openface,sumsuddinshojib/openface,Alexx-G/openface,xinfang/face-recognize,nmabhi/Webface,nhzandi/openface,francisleunggie/openface,nhzandi/openface,sahilshah/openface,Alexx-G/openface,sahilshah/openface,nmabhi/Webface,cmusatyalab/openface,sumsuddinshojib/openface,cmusatyalab/openface,sumsuddinshojib/openface,nmabhi/Webface,xinfang/face-recognize,xinfang/face-recognize,Alexx-G/openface,Alexx-G/openface,nmabhi/Webface,cmusatyalab/openface,sahilshah/openface,francisleunggie/openface,nhzandi/openface,sumsuddinshojib/openface