My game is moving slowly and i need help

1. Hello, so my game keeps moving very slow and it only happens on the pokemon world server. and it happens when it downloads the recourcepack. With pokewars and skyblock it works perfectly fine after the download, so i'm very confused. I've also tried switching servers but it would auto download and start glitching again.

 

I have also had trouble loading my resource pack properly. The lag issue and the chunks that won't load makes the Champion rank flying perk really hard to use! Some people have it and others don't however, when all the chunks have loaded in, the lag seems to go. Please fix the horrible issue.

 

i've noticed that earlier, But my pc isn't able to download optifine for some reason.