I will write this once, but the list includes example songs, and an obvious volume warning for any of them.

• DJ SHARPNEL/SHARPNELSOUND was my entry into Speedcore back in 2011. Not the song I discovered them with, but one favorite is Marunouchi surviver (especially because Penguindrum later became one of my favorite anime)
• m1dy, where the song I found of him first is still one of my favorites: Cold Pizza
• t+pazolite, nowadays does a lot of more J-Core adjacent stuff, but older stuff, around the time I discovered them, was definitely faster. One of my favorites of them is Distorted Lovesong
• goreshit. Mostly breakcore, but also a bunch of speedcore in the older releases. I'll link a favorite album here too, even if it's breakcore: semantic compositions on death and its meaning
• The Quick Brown Fox. I have too many favorite songs of them, so here's a pick: Shut Down Everything
• Kobaryo, which I listen to a lot lately. Pick here is Sequence Breaker
• Laur, also one of my current listens. Not full-on speedcore here either, but we'll have Viyella's Nightmare as a pick here.

Sure that I forgot some when making this list, but that's what came to mind when writing this at least.