Greatly improved speed if image is not a gif

[indykoning]

Using this module before with 10 images (Not gif images) took 4 seconds in total.
Using this module with this edit it will be able to do this in 1 second.

Those benchmarks were done on images that have already been cached already.

All the file operations are relatively heavy, instead of starting with those do a very simple check if we are even dealing with a gif.