[R] R crashing with ggplot 2d histogram

[zapata at zib.de]

Hi! R newbie here. I wrote a script for a correlation plot, a 2d histogram
(heatmap-like) with ggplot. I've run it before with a smaller dataset and
it runs on my laptop and does what I want. Now I've extended my dataset
and R is crashing after the last line which is to generate the plot I
guess. I get the R session aborted / fatal error message.

My new dataset is composed of time series for two variables. For each
variable there are 50 time series with 15.000 values each, so it's in
total 15000*50= 7.5E5 coordinates for this 2d histogram. Do I have a
memory problem here or is it just a script issue? Any suggestion to make
it run? An eli5 answer would be appreciated, my R experience is relatively
low, I just use it here and there for plotting. Thanks!

Carlos Zapata