There is a new version of Firestorm viewer that was released yesterday (August 8) -- version 220.127.116.11527 that is fast, full of features, and sharp and clear. At first glance, it appears to be a great improvement over the current version. I give it five stars.
The only caveat, and I am not sure if it is even an issue, is that I noticed some "flashing" when I first rezzed into to our skybox. I have a powerful new computer based the latest Intel I7 running an NVIDIA GTX 970 graphics card, and usually operate on ultra at maximum everything. The problem went away, and was restricted to our parcel only. Still, this is the type of issue can indicate a graphics bug or perhaps a leftover file from a prior install. It went away when I visited Lemon Beach for a photography session.
You can find the new version of Firestorm here. Downloads are fast even though the release was only out for three hours when I accessed the file: