[krzysztow]

Spring is a one thing, Java is really another. One can use Java without reflection, and then the cold starts are really reduced. Additionally, there's a GraalVm which is optimized VM which should be even faster. On top of that, if the reflection is not used, these days one can compile Java to the native image, which has none of these problems.

[dimitrios1]

When you say fast though, you really are talking in comparison to other methods of using Java on Lambda. But compared to using something like Go, they are all slow.