MacBook Pro Encountering High Latency

Solution 1:

Edit: Apple released two updates for the MBP this week, including an EFI update. While neither update explicitly mentioned wireless connectivity, the update seems to have partially fixed the problem. After installing both updates, I get a pretty consistent 3-5 ms ping with a very very occasional spike to 100. At least it's much better than before.

In the meantime, the trick below still works if you want a 1 ms response instead.

There's an interesting tip from someone on Apple's discussion forums that can work as a workaround.

It appears that if the network card is inactive for more than 200 ms, it powers down and has to be powered up to send network traffic again, hence the random spikes. But, if you can keep the network card active (at the cost of a small amount of CPU power and some extra traffic), then the latency goes away.

The command recommended by seanfromcolumbus was:

sudo ping -i .2 192.168.1.1

(The -i .2 specifies an interval of 200 ms)

Indeed, with this running, I get consistent results of <2 ms.

Original Post

Solution 2:

I did a Time Machine backup and wiped out my existing installation then did a fresh install of Snow Leopard. After that I installed the 10.6.7 combo update just to verify that it was the cause of this problem and it IS! I did yet another fresh install and then I only installed the 10.6.6 combo update and the rest of the regular application updates. Now everything is back to normal. With 10.6.7 I was getting insane ping response times back from the gateway... like 350ms...800ms..600..245.. etc... now everything is back to normal and I get the expected <1ms or the random 1-5ms... I don't know what Apple did with 10.6.7 but it destroy's wifi.