Speed estimation for lmer?

so if my response is on a continuous scale, is there any difference between

lmer(y~fixed+(1|random)) and
glmer(y~fixed+(1|random),family="gaussian") ?

the output is the same but since reading the above i'm wondering if
'plain' lmer is written to run faster?

Those calls will be equivalent but if you look closely at the object
produced by the glmer call you will find that it has been quietly
replaced by a call to lmer.  There is a section in glmer that reads

   if(family$family == "gaussian" && family$link == "identity") {
       mc[[1]] <- as.name("lmer")      # use lmer not glmer
       mc$family <- NULL
       return(eval.parent(mc))
   }