How to improve the deserialization time of ATNSimulator?

ANTLR4 is a great tool.

But I have faced a performance problem.
As @ericvergnaud said，[“We should focus on deserialization time, and memory size after deserialization.”](https://github.com/antlr/antlr4/pull/3505#issuecomment-1025116471)

I have used ANTLR 4.9.3 to generate my CssParser.java and Csslexer.java from [css3.g4](https://github.com/antlr/grammars-v4/blob/master/css3/css3.g4)

Both the two class spend about 70ms - 100ms to deserialize the _serializedATN which is a long String.

Is there any way to decrease the deserialization time of ATN？

Thank you very much for your support!

Start with the generated CssParser.java and CssLexer.java from css3.g4, focusing on their _serializedATN deserialization path. Measure the reported 70–100 ms cost with ANTLR 4.9.3 and compare both generated classes. Done would require a defined, validated approach that reduces deserialization time without breaking parser behavior.

Written by the indexing model from the issue text.