When you're cutting tomatoes for sauce, you don't need to remove the seeds, and you don't need perfect little cubes. Any old shape will do. So save time by chopping in stacks.
Begin by cutting the cored tomato into slices, and then make stacks of two slices each. Cut through each stack, rotating 90 degrees after each pass, until you've got your desired size of tomato chunks.
If, on the other hand, you're making garnish or pico de gallo, you may want something a bit less rustic.
Tip No. 1: Take your time.