Hi, I think this is caused by a couple things. Lemmy has a ratelimit on the number of API requests you can send and also marking posts as read and a lot of filters cause the app to pull more since some content gets filtered out.
I think a possible solution from my side might be instead of sending the read calls right away (so quickly scrolling past everything will send a lot of API calls quickly) would be to queue them and release it in chunks.