How to avoid garbage collection when using Json? - libgdx

Question

I'm currently loading my level with the Json classes. Problem is, the application lags at the beginning which is probably due to the GarbageCollector removing all my unused JsonValue objects. I don't currently know, how to fix this, any advice would be appreciated,
the WorldLoader class with the json stuff, code looks like much, but is pretty straight forward:
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);
}
}