Is my code ineffecient or needing the garbage collector? - libgdx

Question

don't know if you're allowed to ask that here, but I wanted to know if my code is inefficient and leaves much work to the garbage collector, because I'm trying to find a source of lag in my game.
Heres the class, which loads the world through json files.
Worldloader.java:
package com.Sidescroll.game.Helpers;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import com.Sidescroll.game.GameObjects.Background;
import com.Sidescroll.game.GameObjects.Platform;
import com.Sidescroll.game.GameObjects.Player;
import com.Sidescroll.game.GameWorld.GameWorld;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.files.FileHandle;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.utils.JsonReader;
import com.badlogic.gdx.utils.JsonValue;
public final class WorldLoader {
private WorldLoader() {}
public static HashMap<String, GameWorld> worlds = new HashMap<String, GameWorld>();
private static JsonValue jsonPlatforms, jsonSpawn, jsonBackgrounds;
public static GameWorld loadWorld(String levelName) {
if(worlds.get(levelName) != null) return worlds.get(levelName);
//load json file
FileHandle handle = Gdx.files.internal("levels/" + levelName + ".json");
String fileContent = handle.readString();
JsonValue json = new JsonReader().parse(fileContent);
jsonPlatforms = json.get("platforms");
jsonBackgrounds = json.get("backgrounds");
jsonSpawn = json.get("spawn");
//loads platforms
List<Platform> platforms = new ArrayList<Platform>();
for(JsonValue pValue : jsonPlatforms.iterator()) {
Platform platform = new Platform(pValue.getInt("x"),
pValue.getInt("y"),
pValue.getInt("width"),
pValue.getInt("height"),
Platform.Type.valueOf(Platform.Type.class, pValue.getString("type")),
pValue.getString("variant"));
platforms.add(platform);
}
//create player
Vector2 vecSpawn = new Vector2(jsonSpawn.getInt("x"), jsonSpawn.getInt("y"));
Player player = new Player(vecSpawn, platforms);
//loads backgrounds
List<Background> backgrounds = new ArrayList<Background>();
for(JsonValue bgValue : jsonBackgrounds.iterator()) {
Background bg = new Background("bin/sprites/" + bgValue.getString("name") + ".png",
bgValue.getInt("x"),
bgValue.getInt("y"),
bgValue.getInt("width"),
bgValue.getInt("height"),
bgValue.getBoolean("front"));
backgrounds.add(bg);
}
worlds.put(levelName, new GameWorld(player, platforms, backgrounds));
return worlds.get(levelName);
}
}