Just seems like it's going slower these days...

Slower, as in less traffic, or slower, as in working slower?
I know that I get a server error if I try to access my seller account, so something is up either way

Slower to load.

I'm going to second this. The site since the last update is nearly unusable. It takes 30 seconds to make one change to a deck list and the loading of card images takes 20 seconds. I'm using Chrome as my browser. Was never a problem before. The site seems to be a little faster when using a different browser like AVG.

Should not be the case, nothing performance related should have been changed. Could you tell me which pages / images you are seeing issues with? How long have you noticed this happening?

I don't know, I've loaded the site up a few times in the past month and it went slow. I believe I opened up a commander decklist and it went slow. I then tried to click on a card to see what the card did, and it took a while to load. Long enough that my attention span drifted to another tab on my web browser.

I've noticed the same performance issues these last couple of months. From what I have seen, when the slowdown occurs any action within the site seems to be affected (i.e. add card, remove card, autocomplete, hover card preview, deck listing, inventory listing/searching to name a few). On average, actions take around 3-5 seconds. On bad days I've seen it upwards of 15-20 seconds per action, at which point I just postpone deck building until it improves. Unfortunately, it tends to fluctuate throughout the day.

fwiw, here is my environment:
Chrome: Version 78.0.3904.108
OS: Mac 10.14.5
Download speed: ~150 Mbps