@wking The current 10^4 example runs to 0.011 seconds using plain old `read.csv()`, adding `colClasses` speeds it up to 0.009, and the `fread()` example takes 0.001 seconds. Timings are on recent workstation with a Xeon and piles of RAM. 10 million rows would create an object using ~76Mb of RAM so probably feasible on modest hardware. 100 million rows would need ~0.8Gb of RAM so possibly beyond the scope of modest hardware. Having a few 10s of seconds run time for the `read.csv()` case is probably OK for a lesson like this as it really will highlight how fast `data.table` can be.