Entity knockback delay and low frame rate

I am playing with the same settings and worlds as I was in 20w21a, and the frame rate is extremely low when opening Minecraft and a world for the first time in the day and throughout the gameplay later on in addition, I notice significant delay between my punches (to an entity) and its knockback effect, even delay in registering I punched (the entity), that includes hittings with weapons and tools.