A correction to my previous post:
after running the example A[,1] and A[[1]] the running time decrease so that
eventually A[[1]] takes 0.025 seconds (according to system.time()) and A[,1]
takes 1.8 seconds.
The ratio of time still 2-digit, but, apparently, the garbage collector is a
good deal faster when memory is already available.
best
Vladimir Dergachev