Using LLVM is not exactly an indelible architectural decision — switching to a bespoke JIT would be entirely possible, it’s just not worth it yet. Moreover, if you want to generate world-class high speed code, you really need something like LLVM. So yes, it’s a bit of a drag but it’s also a massive enabler of critical performance. That’s the real reason the project continues to use it.

There are a number of approaches to reducing latency further, which are being pursued. The most promising current avenue is better tooling around system images (compiled executables with additional functionality beyond the core language pre-loaded): generating them faster, generating them incrementally (load one, add a few things and produce another), and generating them automatically for the set of packages in the current active project (not feasible until the first two are done). That will give an experience comparable to compiled languages.