[R] Parallel code runs slower!

[Santosh Srinivas]

My parallel code is running slower than my non-parallel code! Can someone
pls advise what am I doing wrong here?

t and tTA are simple matrices of equal dimensions.

#NON PARALLEL CODE

nCols=ncol(t)
nRows=nrow(t)
tTA = matrix(nrow=nRows,ncol=nCols)

require(TTR)
system.time(
for (i in 1:nCols) {
	x = t[,i]
	xROC = ROC(x)
	tTA[,i]=xROC
		
	}
)

   user  system elapsed 
 123.24    0.07  123.47


# PARALLEL CODE

nCols=ncol(t)
nRows=nrow(t)
tTA = matrix(nrow=nRows,ncol=nCols)

require(doSMP)
workers <- startWorkers(4) # My computer has 4 cores
registerDoSMP(workers)
system.time(
foreach (i=1:nCols) %dopar%{
	x = t[,i]
	xROC = ROC(x)
	tTA[,i]=xROC
		
	}
)

# stop workers
stopWorkers(workers)

It is taking ages!

Thanks,
S