Java literally runs on smart cards, including SIM cards: https://en.wikipedia.org/wiki/Java_Card https://en.wikipedia.org/wiki/Java_Card — and did so since the

Java literally runs on smart cards, including SIM cards: https://en.wikipedia.org/wiki/Java_Card https://en.wikipedia.org/wiki/Java_Card — and did so since the 90s. My guess is, applets were crashy for different reasons than CPU speed.