One might expect the sum of the
tracert latencies to equal 267ms:
Traceroute involves sending UDP packets to each node along the way, and waiting for its timeout response (then moving on to the next node), whereas a ping is just forwarded. What you're seeing is the time it takes for each node to respond to the request instead of just forwarding a small packet.
This is a pretty nice explanation of the whole process, and the differences.
Have a look at the performance section, which explains also why ping isn't a particularly accurate method for determining latency.
Routers tend to give timeouts and echo response handling lower priority than packet forwarding. This allows the switch to operate more efficiently as forwarding is much simpler to process than generating a new ICMP responce. As a result busier switches will take longer to generate the response.
Some switches may have ICMP generation disabled which makes diagnosing network issues with them diffficult. Other may occasionally get busy enough that they fail to respond.
If you use a tool which displays the IP address of the routers along the way, you will usually see the switches which are slower are core switches in major cities. My preference is