Render a lot of same images

In my previous comment I didn’t focus on the “same” part of your question, thinking that they were different images.

For a grid of the same image covering the whole screen a texture also works:

PImage img;

float columns = 64.0;
float rows = 64.0;

void setup() {
  size(1000, 1000, P2D);
  img = loadImage("berlin-1.jpg");
  textureMode(NORMAL);
  textureWrap(REPEAT);
  noStroke();
}

void draw() {
  beginShape();
  texture(img);
  vertex(0, 0, 0, 0);
  vertex(width, 0, width/columns, 0);
  vertex(width, height, width/columns, height/rows);
  vertex(0, height, 0, height/rows);
  endShape();
}

Modified version of Examples > Topics > Textures > TextureQuad

With this approach the performance is not affected by the number of columns or rows.