GIMP not responding on high file sizes.

[rich2005]

If Ofnuts suggestion does not improve performance.

You could partly abandon Gimp and use command line applications for the unoptimise part, that might help (or maybe not ) It might save a little time only partially using Gimp.

This old application gifsicle https://www.lcdf.org/gifsicle/ can unoptimise screenshot: https://i.imgur.com/eBFat0O.jpg

Code:

gifsicle.exe -U input.gif -o output.gif

Another approach might be split the gif up into separate frames using ImageMagic (IM) http://www.imagemagick.org This will unoptimise and render each frame as a png https://i.imgur.com/shRQcuJ.jpg

Code:

magick convert -coalesce input.gif output%05d.png

Then it depends on what you are interlacing? If an overlay of a single logo, might be easy, maybe using Gimp BIMP plugin on a folder full of files. Another animation to interlace, not so easy. IM has a full (confusing) page of various procedures. http://www.imagemagick.org/Usage/anim_mods/#merging

You can also use IM to easily combine back to an animation: https://i.imgur.com/VaZvQf9.jpg

Code:

magick convert -delay 20 -loop 0 *png output.gif