Yeah, it was that last bit about animated terrain I missed.
However I do want animated terrains for some of the things so I ended up just resizing the animated files in paint.net down to 128x(whatever the height needs to be, 2048 down to 512 for example). I can live with a couple of blocks being smaller res for the animations they provide.
Also thank you very much for replying. Don't know how often you get it, but I want to let you know I greatly appreciate your resource pack.
The weird thing is that turning off 'Animated textures' does nothing visually, for what I've seen. I'm still not sure why and what is causing the lag.