Thanks!
I think I know why you are seeing that issue, I should be able to fix it in the plugin. Thanks for the bug report and supplying an example project, which is always very helpful for debug.
Meanwhile for further testing in your project add a rotating sprite in your layout. This will make sure the GIF render to C3 happens every frame, including at the start.
On the memory side, the GIF is not storing much data in the GPU memory, but a lot in CPU memory (each decoded frame.) So the memory usage may show up in another way, just something to be aware of.