[R] pch="." plots much faster

[Charles Plessy]

Dear list,

I realised by chance when analysing a 1521862 × 8 matrix that plotting
was much faster when using "." as the argument of `pch'. I was just
wondering if there were other ways to get this speed improvement: it is
otherwise quite difficult to explore such big matrices, especially given
that X11 redraws the plot whenever its window is covered/uncovered by
another window, or when I switch virtual desktops.

Best regards,

-- 
Charles Plessy,
Wakō, Saitama, Japan