Grunt watch tasks seem to take a very long time

Question

I'm running two simple tasks that run for <100ms each but when run under the watch command the two combined tasks are taking ~8 seconds in total (there seems to be an overhead of 3.5 seconds per task). I'm using it with live-reload for development and I'm finding it very frustrating. I tried setting spawn to false but this seemed to break it and none of the associated tasks were run.

Here's sample output from when a sass file is changed.

>> File "app/styles/main.scss" changed.

File "app/styles/main.css" created.

Done, without errors.

Elapsed time
loading tasks   4ms  ▇▇▇▇▇ 9%
sass            1ms  ▇▇ 2%
sass:dist      39ms  ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 89%
Total 44ms
Completed in 3.862s at Mon Nov 18 2013 17:05:57 GMT+0000 (GMT) - Waiting...
OK
>> File "app/styles/main.css" changed.

Running "copy:styles" (copy) task
Copied 1 files

Done, without errors.

Elapsed time
loading tasks   4ms  ▇▇▇▇▇▇▇▇▇▇▇▇ 24%
copy:styles    13ms  ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 76%
Total 17ms
Completed in 3.704s at Mon Nov 18 2013 17:06:01 GMT+0000 (GMT) - Waiting...
OK
>> File ".tmp/styles/main.css" changed.

... Reload .tmp/styles/main.css ...
... Reload .tmp/styles/main.css ...
Completed in 0.000s at Mon Nov 18 2013 17:06:01 GMT+0000 (GMT) - Waiting...

Using grunt 0.4.1 (and grunt-cli 0.1.11) on node.js 0.10.20. Running on 2012 Macbook Air (OS X 10.8.5)