Looks like I had already bumped the HEAP size up to 8MB for this demo, so 45 second gif I would have thought worked, however, you could try changing this line in mkenv.mk
LNK_FLAGS = --defsym _HEAP_SIZE=0x800000 -nostdlib -T "$(TOOLCHAIN)/$(PLATFORM)/lscript.ld" -R "$(TOOLCHAIN)/$(PLATFORM)/stdlib_0.lib" -Map="$(BUILD)/$(PROJECT).map" --gc-section -L"$(TOOLCHAIN)/$(PLATFORM)" ${TOOL_LIB}
The _HEAP_SIZE symbol control the size, the default for VEXcode if this is not defined is just 1MB, for this demo I had bumped to 8MB, you could try 16MB and see what happens.
--defsym _HEAP_SIZE=0x1000000
I found some gif’s that are not supported by the library I baed this code on, that may be another cause of the issue.