FSPViewer

FSPViewer is a simple tool you can use to view panoramic images. It offers support for JPEG, TIFF and FSPViewer Panorama files, and it doesn't require installation.
The program is designed for equi-rectangular (spherical) panoramas and has a built-in speed tester. It doesn't contain complicated options or configuration parameters, making it accessible to all types of users.

No setup necessary

You can drop the downloaded files in any location on the disk and just click the .exe to launch the application. Otherwise, you can keep it stored on a USB flash drive to be able to directly run it on any computer with minimum effort and no previous installers. More importantly, it doesn't modify Windows registry settings.

View panoramic photos

It's packed in a user-friendly interface which consists of a normal window with a plain and simple structure, where you can open a panorama file and change the perspective using the mouse.
It's possible to adjust the contrast, enter fullscreen mode, hide the toolbar and status bar, access a list to view hotspots, as well as show or hide hotspots. Speed tests can be performed to find out the frames per second. As far as general preferences are concerned, you can enable a bilinear, Lanczos2 or Lanczos3 interpolator.

Evaluation and conclusion

As we expected, it didn't put a strain on the overall performance of the computer in our tests, running on a low amount of CPU and RAM. Although it hasn't been updated for a while, it worked smoothly on newer Windows editions, without triggering the OS to hang, crash or prompt error messages.
To wrap it up, FSPViewer offers a straightforward solution for opening files to view panoramic photographs, and it can be handled with ease by any type of users.