Mike,
It may cause a slight page load increase, but will be offset by slightly less processing time from your server to generate the page itself. Some servers also automatically perform gZip compression, which means that the Joomla setting should be off anyways. I don't know if your server is configured that way.
Again, we do plan to investigate, but this is *not* an issue with JFBConnect. We set the tags on the page, but something is going wrong with the compression that Joomla is doing to make the page unreadable by Facebook. It may also be a Facebook issue. We will do whatever we can to fix it, but I'm not sure we'll be able to.
I'm glad you got things going for now though, and definitely keep us posted if you run into anything else.
Thanks,
Alex