Input Update extremely slow when Mousing over Window

[Thygrrr]

When I mouse over my game view (e.g. wiggling the mouse in a small circular motion), I am seeing extremely long frame times. They instantly get better again when I let go of the mouse.

These get worse over time / seemingly as DOTS physics load increases (a little).

The kicker is, if I don’t focus my right screen (which holds the game view), the frame rate stays fine. Even if I completely disable my one input that takes something from the mouse (code attached), this doesn’t get better.

using UnityEditor.PackageManager.UI;
using UnityEngine;
using UnityEngine.InputSystem;

public class MouseCursor : MonoBehaviour
{
    private RectTransform _rt;
    public Texture2D cursor;
 
    public Camera uiCamera;

    public static Vector2 pitch;
 
    private void Start()
    {
        _rt = GetComponent<RectTransform>();
        //Cursor.SetCursor(cursor, new Vector2(15,15), CursorMode.Auto);
        //Cursor.visible = true;
    }

    private void Update()
    {
        var position = Mouse.current.position.ReadValue();
        _rt.position = position;

        var relative_to_center = (position - Screen.safeArea.center);
        relative_to_center.x /= Screen.width;
        relative_to_center.y /= Screen.height;

        relative_to_center *= 3.0f;

        if (Mathf.Abs(relative_to_center.x) > 1)
            relative_to_center.x = Mathf.Sign(relative_to_center.x);

        if (Mathf.Abs(relative_to_center.y) > 1)
            relative_to_center.y = Mathf.Sign(relative_to_center.y);


        relative_to_center.x = Mathf.Pow(relative_to_center.x, 3);
        relative_to_center.y = Mathf.Pow(relative_to_center.y, 3);
     
        pitch = relative_to_center;
    }
}

This is with Input System 1.1 on Unity 2020.1.

Question: Does Inputsystem do anything with, or make any assumptions about DOTS, any of its system groups, or DOTS physics in particular? Going on a limb here, but that was the last thing I was working on.

I repeat: There is no mouse input code in the game now, and it still does this.

[Thygrrr]

Wow.