R, looking for a faster and more efficient way (package, code, parallel processor) than basic R

I am using basic R for combinations.

For example, let's say I have a matrix with 2 rows and 5 columns:

 z<-matrix(c(1, 2, 1, 3, 2, 2, 1, 3, 2, 1),nrow=2,ncol=5,byrow = TRUE)

[,1] [,2] [,3] [,4] [,5]

[1,]    1    2    1    3    2

[2,]    2    1    3    2    1

      

        
        
        
      

    

I am using the following code for combinations of 3 column sets:

l<- apply(X = combn(seq_len(ncol(z)), 3),MAR = 2,FUN = function(jj) {apply(z[, jj], 1, paste, collapse="") })

      

        
        
        
      

    

This will export what I need:

[,1]  [,2]  [,3]  [,4]  [,5]  [,6]  [,7]  [,8]  [,9]  [,10]

[1,] "121" "123" "122" "113" "112" "132" "213" "212" "232" "132"

[2,] "213" "212" "211" "232" "231" "221" "132" "131" "121" "321"

      

        
        
        
      

    

The problem starts when I use big data in a matrix, for example when I have a matrix with 15000 rows and 17 columns and I need combinations of 10 column sets.

In this example, this export takes a very long time.

Is there a faster and more efficient way than basic R (maybe some packages or code or using parallel processors) for this example combinations?

I am using Windows 7 64bit, FX 8320, 16GB RAM.