Quote:...My 500 frame animation is 480 P which was the width and length being 854. I have not tried dimensions exceeding 480 p for GIFs...
That makes more sense for an animated gif, which comes from an older days when images sizes were much smaller. Still on the large side.
Quote:..I use GAP plugin which has "Split video into frames" option...
You are lucky that GAP works. It is an old plugin. It does use ffmpeg (an old version). Guessing that is how it renders frames
Quote:...The video lengths would not be more than 15 seconds . Cuz as a GIF ,that's long enough interval to loop.
Certainly is

Quote:..At the bottom of the screenshot, File size says 500.png(1.4) GB.What does that imply..That is the layer name and the size of the image in memory. If you do any editing then expect that to grow. One of your problems might be the number of undo levels. see Edit -> Preferences -> System Resources Minimal number of undo levels. Try setting that to zero.
Quote:...to check file sizes in GIMP, I check them at Image -> Image properties menu and my file(.xcf) size was 1.5 GB.
That is a saved file. xcf is compressed. It is a large file. Even larger when opened and uncompressed.
Can not really give much advice. If your original video is 30 fps, use every 3rd frame. Gets you down to about 150 frames = 15 seconds @ 100ms timing. As an animation you will never notice the difference.