OnTriggerEnter2D first collision causes lag/freeze

Hey all, I'm currently developing a mobile game and I ran into a small problem. When my player first collides with an enemy, the game freezes for a bit.

The weird thing is that this happens only when first time OnTriggerenter2D is called. Enemies that collide with my player afterwards do not cause any lag. I profiled the game and it shows that three things cause this issue, specifically: Physics2D.CompileContactCallbacks, Physics2D.SendContactcallbacks and Physics2D.SendTriggerContactCallbacks.

My player has a dynamic rigidbody2D attached as well as BoxCollider2D that has set OnTrigger to true. The same applies to the enemies, except the rigidbody2D is set to kinematic.

Here's a screenshot from the profiler: https://i.imgur.com/RDVHeXg.png

I'm testing it on Samsung S4 mini.

Any ideas how to fix this?

Thanks!