Increase FPS on ESP32

[bbuster2]

I am using an ESP32 (16mb) with a 3.5" ILI9488 display.
Updating the display is really slow.

I just read an article about PSRAM on an ESP32.
Some boards have 4MB, some have 8MB.

I have a custom PCB with the WROVER chip (so no development board).
To check how much my chip has, i used this code:

  log_d("Total heap: %d", ESP.getHeapSize());
  log_d("Free heap: %d", ESP.getFreeHeap());
  log_d("Total PSRAM: %d", ESP.getPsramSize());
  log_d("Free PSRAM: %d", ESP.getFreePsram());

This is the output:

[   516][D][main.cpp:50] setup(): Total heap: 299216
[   516][D][main.cpp:51] setup(): Free heap: 273060
[   516][D][main.cpp:52] setup(): Total PSRAM: 4192139
[   521][D][main.cpp:53] setup(): Free PSRAM: 4192139

I saw this as a suggested external PSRAM chip (2x 8MB if i am correct): https://www.electrodragon.com/product/2pcs-ipus-ips6404-iot-ram/

Does (and if so, how) this work?
How much PSRAM does my chip have (a few hundreds kilobytes??) and will adding 16MB PSRAM dramatically increase fps?
// update, i saw 0 total PSRAM but needed to add

	-D CORE_DEBUG_LEVEL=5
	-DBOARD_HAS_PSRAM
	-mfix-esp32-psram-cache-issue

Does this mean i already have 4mb psram?

Or doesn't it work like this?
I sometimes see video's where an ESP32 is used to show images / video's and the FPS is way higher than what i can get with putting sprites, lines, rectangles etc on the display.