This is something you need to be careful about. SAS will tabulate the data like lightning, but it will take forever to render the results into html if the result set is large. Fortunately, all you need to do is Tools | Options, and on the Results General tab turn off all of the Result Formats tick boxes. I assume you're saving your results to a dataset.
For large problems, PROC TABULATE has a restriction of 2^32 result cells. If you need to exceed this, PROC MEANS has no limits that I've found; I think it's faster than TABULATE as well.