It is pretty strange that i didn’t cover this topic in previous posts. So, i stand corrected and posting it now!
@ FIRST: WHAT IS DEMOSCENE?
In this quick breakdown i’ll point to the most coolest demoscene stuff out there.
▓ IBM PC [DOS/WIN]
In early 90s finnish coders from Future Crew brought phenomenon of demoscene to masses.
FUTURE CREW - SECOND REALITY 
Demo size: 2Mb
The Black Lotus
are Swedish Atari/Amiga hackers.
First TBL demo, which i saw back in 2000 on PC platform.
I can’t understand how they’ve managed to pack these graphics and sound into 64Kb demo clip.
The answer was quite straightforward: all demo stuff like gfx and audio were generated on the fly from scratch.
No pre-generated textures or sound samples were used.
TBL - STASH 
Demo size: 64kb
German hackers from Farbraush simply blowed up demoscene in late 00s.
FARBRAUSCH - FR-041: DEBRIS 
Demo size: 180Kb
▓ ATARI & AMIGA
The Black Lotus
is famous for their top quality Atari Falcon
TBL are doin’ pure magic on those 60Mhz machines of the time.
Hacker skills and software optimization are jaw-dropping.
TBL - STARSTRUCK [2006-2018]
Demo size: ~18Mb
Platform: hi-end 60 Mhz Amiga 4000 based around Motorola 68060 CPU
First version was released in 2006.
2018 remaster brought some code optimizations and bugfixes.
TBL - OCEAN MACHINE 
Demo size: ~10Mb
AMIGA 1260 VS ATARI FALCON 060
As you can see Atari demo runs a bit faster due to some hardware and software advantages, like:
- dedicated DSP for sound processing [audio consumes less than 0.5% of CPU time]
- more optimized video memory management
- faster RAM [SDRAM vs EDO/FPM]