People keep bringing this up but Java Card is a really small subset of Java so you can't draw any conclusions. In particular it has no garbage collection, which is easily the heaviest part of Java.

> Many Java language features are not supported by Java Card (in particular types char, double, float and long; the transient qualifier; enums; arrays of more than one dimension; finalization; object cloning; threads). Further, some common features of Java are not provided at runtime by many actual smart cards (in particular type int, which is the default type of a Java expression; and garbage collection of objects).

To add on, here's a quick intro to the headache that goes into writing Java for GSM cards - https://youtu.be/31D94QOo2gY?t=607

But writing Javacard for ICCs is like writing another language and ecosystem entirely. The syntax is familiar but there the comparison kind of ends.