Is there an overview somewhere of the Kotlin collections implementations time and space complexities for different operations? Most of them are pretty standard, but nonetheless it would be nice to have a quick overview somewhere.
Unfortunately, the Kotlin docs aren’t very good at that sort of detail.
The Java docs are generally much better, so you can check those for any classes defined in the JRE.
Otherwise, I think your best bet is probably the source code. In some cases, the Kotlin classes end up using Java ones, which can give you a good idea — though if that’s not documented, then it’s subject to change in future versions and not guaranteed.
Also make sure to check out Kotlinx Immutable Collections, which has a lot of documentation about time complexity