There *are* very good reasons not to use Facebook’s Like button regardless of its memory footprint.
The tests were made with Firefox 3.6.10 on Vista with Firebug and some other plugins enabled on a client’s WordPress blog. I have recorded the amount of iframes, peak memory value (the highest value during or shortly after page load) and idle memory value (20-30s after page load).
Keep in mind that this is by no means scientific. YMMV.
|Amount iframes||~MB peak||~MB idle|
Obviously idle memory footprint scales at about 1,0-1,2 MB per iframe. That is quite a lot.
And do remember that each iframe comes with its
- own HTML,
- inline CSS,
- external CSS and
- at least one image.
I have not counted the exact amount of requests though I expect ~4, maybe ~5 HTTP requests per Facebook Like button iframe. With 40 of them on one page that sums up to 160 HTTP requests just for the Facebook Like buttons.
From a Green Computing point of view it is quite insane.
My conclusion is if you *really* want to use Like buttons that you do not to put more than a dozen or half a dozen Like buttons on a page.