Cartoon animations don't require accurate frame speed. Or a massive number of frames.
A Technicolor action movie requires a lot of frames with lots of pixels.
Which is why digital techniques like MP4 were developed. To compress images and minimise the quantity of data.
I can show you how to compress your bitmaps on a Uno e.g. with Run Length Encoding. GIF uses a more sophisticated method which is too complex for a Uno.
"SD.h" needs some working SRAM, your OLED needs some working SRAM, each frame needs some working SRAM.
With a Uno, you have to use every trick in the book to economise SRAM. Which means that things will be SLOW.
Please just try my example code.
David.