Duplicating my answer to the identical question in cssm:
Please clarify what you mean by your "system time".
If you mean "cpu time", then
tic;
%your code here
ms = round(toc * 1000);
If you mean "elapsed time", then
t0 = clock;
%your code here
ms = round(etime(clock,t0) * 1000);
However, if this needs to be done automatically, whenever something is displayed, without you having to change the code (that you might not have written), then you are probably going to have to override the system routine named "display", which probably isn't a wonderful idea.
