Lagging while using Texture Pack..

Hi guys, I have a big problem with my texture pack that I'm currently using. Everything seems fine if I go to the Minecraft Singleplayer and try to play without the texture pack, I have around 60 FPS stable. But one time I told myself that I can play with the texture packs because the game just looks better, so I found this texture pack Fresh Animations Texture Pack 1.19.1 → 1.18.2 | TexturesPack.com and then downloaded it. I put it into the Minecraft and start using it, but suddenly the FPS dropped to 10-20 FPS, I don't know why. Can anyone help me out please? I have 4GB PC and the game is allocated to 1GB.