Ditto, do not go straight through. I've taken I-95 around coming from the south. Sometimes all the way to I-90 merges with 1 and sometimes I-93 to I-495. I have not resorted to 495 all the way around but it depends on the day, and I haven't made the trip in the summer. That was winter traffic going skiing which was probably lighter, but it was Friday trips.
Google maps and traffic is your friend and expect red areas to get worse before you get there. You might decide 495 is less hassle even if the interior loop is potentially faster. I'm sure it's traffic filled regardless but Boston isn't that big which helps.