Severe Lag when using /summon in functions

Basically, when I summon entities in areas that aren't fully loaded by a player yet (from a function) when a player loads that area in, there will be severe lag and frame drops, even on a single player world.

Steps to reproduce:

• Set up a line of 4 ticking areas (radius 4, circular)
• Run a function that summons an entity in all 4 areas while the player is in the first area
• Go through the rest of the ticking areas and you will start to experience extreme lag
• The first area shouldn't lag