Dear George,
you are quite right, sometimes there are issues with Interpreter when applied to many entries. In fact I have another version where I use a bit more of input modification and then the function DateObject instead. This is much faster and never appears to cause problems.
Interpreter is more concise though and takes away lot of the fiddling with the data. I don't think that this is an issue of the OS or laptop performance. I used simple MacBook to generate the plot, but also checked on a couple of MacBook Pros, an iMac, a windows machine and a MacPro. The internet speed seems to be important. In another post people suggested that also the Wolfram Server you connect to is quite important for the performance.
Best wishes,
Marco
