Seems to have recovered now.
Discussion
I am interested in knowing any details you might provide. I have been hunting this slow downs for months now :(
It might be a relay that is too slow at the moment. I think if the app receives 1 message a second (super slow) it would be updating the entire feed every second and that could create issues.
My relay setup is minimal with nostr.wine.
Can't give you much more information I'm afraid.
Will monitor for it happening again.