I have a datafile with a couple dozen rows and 256x256 columns which I can use to plot and fit data as expected when I only access individual data columns. (e.g. plot 'blubb.txt' u 1:3).
If I try to manipulate the data columns (e.g. plot 'blubb.txt' u 1:($3-$1) ) gnuplot locks up a core and quickly crashes when it hits the 32bit memory limit.