It feels like my picking speed is very limited, especially with write picking.
What is causing this?
Am I picking incorrectly? Am I positioning my wrist/arm wrong?
Do I have weak wrists? What can I do to strengthen my wrists?
Am I not practicing correctly to improve speed?

I'd really like some help please.
try to minimize your movement coming off the string, if you can keep your pick extremely close to the string after hitting it, u can increase ur speed back and forth. and just try building up speed gradually like starting with quarters, then 8ths, then 16th, the 32nds and so on. Maybe a metronome would help so u could try and count how many u can get in between beats.
a metronome helps a metric **** ton. Maybe you can also try using a softer pick. And it sounds like you already know that its mainly in the wrist.
Yeah I keep hearing that I should use my wrist and not my elbow to pick, but I really want to move to that but I feel so slow and sloppy. I like to play fast metal stuff so that's a problem.

Does anyone know a good Metronome VST?