Methinks I shall ignore the robotic comments and focus on what I like.

I'm kind of confused on a 4 core device like a Samsung while simple download threads seem to be stalling when they work fine on Linux

Do not comment I will ignore you dead people

ok tsundere

Considering your typical OS workload has upwards of 200 processes running, 4 cores or 100 makes little difference.

You have contention. Cellphones are usually much more biased to keeping foreground processes running, for obvious reasons, to the point it heavily impacts other tasks.

But still, downloading is still I/O.

I/O is inherently serial. No amount of multithreading will make it go any faster.

You want asynchronicity, not parallel processing.