Recently, Amazon released a update for the kindle fire. (Version 6.3). This update includes some new features, and the occasional stability/bug fixes. I myself can confirm that this update does fix some speed and wi-fi issues for me (my kindle would have trouble connecting to any wifi network after a certain amount of times). For the full changelog, visit amazon’s website.
You should also check out an Amazing Article at lockergnome about making your Kindle look like its running Ice Cream Sandwich! Great stuff, i already did it and love the change.