Seems to miss purges when used with Jetpack comments

[sjgibbs]

I don't have data (see #23) but it seems I get a more responsive user experience if I disable jetpack comments.

I let Jetpack remain active but disabled the comments feature and comments appeared instantly.

My test process was to leave a comment in one browser (chrome) and then switch to a rarely used browser (IE) to see the comment. Without Jetpack comments it appeared immediately.