Apologies if this type of question is not allowed. Its very general and vague, and I am not expecting a "solution" from anyone, but just wondering what people smarter than me, particularly networking folks, might have to say about a strange observation I've had.
I've been playing with youtube-dl to fetch content from various sources. I've run into an issue lately where I will fetch a file from a particular set of sources, and the download time will be dreadfully slow, sometimes to the point of dropping the download altogether. Sometimes the file download will start off fast, and slow to a crawl, and sometimes it's slow from the beginning. I do know that the former case is pretty well documented, given how streaming services tend to handle their streamed media distribution.
I know there are many factors involved, including my internet connection, potential throttling on the server side, and probably a million other things. However, I did notice something that seems strange. I've tested it more than a handful of times, and it doesn't seem like a mere coincidence.
Firstly, I should mention that, while downloading from source X is slow, if I kick off a download from YouTube, it tends to run pretty quickly. They have a big network infrastructure built to handle mass streaming, so no big surprise there. But, in my mind, this rules out my network connection, and it also rules out youtube-dl being slow. Technically, each upstream resource uses a different internal scraper logic within youtube-dl, but I still have no reason to believe it's their code.
My observation is this. When the download from source X has slowed to a crawl, if I kick off a simultaneous download form youtube, that one will move much quicker, and, more curiously, I notice that the original download from source X tends to speed up significantly. To a lesser degree, the same thing seems to happen if I am downloading from source X, it's very slow, then I start watching netflix or some other streaming-intensive media in my browser.
I don't think this is my imagination or placebo, as I've tested many times. I've also noticed that if I kill my simultaneous YouTube download, I will notice the remaining download from source X slow back down to a crawl almost instantly.
Those of you out there with deeper knowledge than I, what might be some hypothetical explanations for such behavior? Or do you all think I've just lost my mind? I've tried some searching about, but haven't come up with much. Maybe I just don't know the proper terminology to search.