You seem to have a misunderstanding of how those other programs work. Most will be using compressed data in some fashion if they’re not real-time generation. PGraphics are uncompressed. Using so many is a recipe for disaster. They’re 500x500x4 bytes (so 1MB) each - almost a GB for the raw data before you get into other things, like caching.
Also, initializing them in a separate thread is wrong. The renderers are not thread safe, and there’s no checking / handoff to the main thread.