plot() in a loop vs multiple curves with a single plot()

Hi,

I have the following code and am wondering whether there is a more
efficient way to plot multiple curves. Maybe somehow accumulating the
data into a single variable, then calling plot once ... Thanks for any
ideas.

for ofile in files:
    d = mlab.csv2rec(ofile, names = ['date','field'])
    ax.plot(d['date'], d['field'])