High CPU Usage?

[bt103]

Complete noob here. By miracle, I managed to get a test program running.
I'm using the 2.4 inch capacitive board 2432S024C.
When I received the board, it had a preloaded demo program running on it (I'm sure you are familiar - it is kinda like a web page).
I can't remember, but the CPU usage was fairly low when nothing is happening (if I recall correctly).

I then setup rzeldent /esp32-smartdisplay and loaded a simple test program to display a button from here.

#include <Arduino.h>
#include <esp32_smartdisplay.h>


static void btn_event_cb(lv_event_t * e)
{
    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * btn = lv_event_get_target(e);
    if(code == LV_EVENT_CLICKED) {
        static uint8_t cnt = 0;
        cnt++;

        /*Get the first child of the button which is the label and change its text*/
        lv_obj_t * label = lv_obj_get_child(btn, 0);
        lv_label_set_text_fmt(label, "Button: %d", cnt);
    }
}

/**
 * Create a button with a label and react on click event.
 */
void lv_example_get_started_1(void)
{
    lv_obj_t * btn = lv_btn_create(lv_scr_act());     /*Add a button the current screen*/
    lv_obj_set_pos(btn, 10, 10);                            /*Set its position*/
    lv_obj_set_size(btn, 120, 50);                          /*Set its size*/
    lv_obj_add_event_cb(btn, btn_event_cb, LV_EVENT_ALL, NULL);           /*Assign a callback to the button*/

    lv_obj_t * label = lv_label_create(btn);          /*Add a label to the button*/
    lv_label_set_text(label, "Button");                     /*Set the labels text*/
    lv_obj_center(label);
}

void setup()
{
  smartdisplay_init();

  auto disp = lv_disp_get_default();
  // lv_disp_set_rotation(disp, LV_DISP_ROT_90);
  // lv_disp_set_rotation(disp, LV_DISP_ROT_180);
  // lv_disp_set_rotation(disp, LV_DISP_ROT_270);

  lv_example_get_started_1();
}



void loop()
{
  lv_timer_handler();
}

However, when it is sitting there doing nothing, it says it is using 70% CPU. Is this normal? Shouldn't it be using nothing, and waiting for an interrupt or somethin'?