set.seed(1)
n=20
df <- data.frame(s1 = paste(sample(0:3, n, replace = TRUE),sample(0:3, n, replace = TRUE),sep="/"),
                  s2 = paste(sample(0:3, n, replace = TRUE),sample(0:3, n, replace = TRUE),sep="/"),
                  s3 = paste(sample(0:3, n, replace = TRUE),sample(0:3, n, replace = TRUE),sep="/"),
                  stringsAsFactors = FALSE)

library(parallel)
split.mat = do.call(rbind,mclapply(1:nrow(df), function(x) {
  mat = sapply(df[x,1:ncol(df)], function(y) strsplit(y, split = "\/")[[1]])
  return(c(mat[1,],mat[2,]))
}, mc.core = 10))

library(data.table)
fwrite(df, sep = "/", quote = FALSE,
       col.names = FALSE, file = "df.txt")

NN <- 2L*ncol(df)

DT1 <- fread("df.txt", sep = "/", select = seq(from = 1L, to = NN, by = 2L))
DT2 <- fread("df.txt", sep = "/", select = seq(from = 2L, to = NN, by = 2L))

options(stringsAsFactors=F)
library(rbenchmark)
library(stringi)
library(tidyr)

set.seed(1)
ncols <- 1
nrows <- 10*1000
strdat <- paste(sample(0:3, nrows*ncols, replace=T),
    sample(0:3, nrows*ncols, replace=T), sep="/")

benchmark(strsplitMtd=lapply(strdat, function(x) strsplit(x,"/")[[1]]),
    striMtd=stri_list2matrix(stri_split_fixed(strdat, "/"), byrow=T),
    tidyrMtd=separate(data.frame(S=strdat), S, c("S1","S2"), "/"))