Elixir 1.15 Speeds Up Compilation and Boot Times

A focused performance release

Elixir 1.15 was released on June 19, 2023. The team described it as a smaller release with focused improvements on compilation and boot times, along with additional convenience functions across Code, Map, Keyword and the Calendar modules. It also welcomed Jean Klingler to the Elixir Core team.

Pruned code paths, faster builds

The standout change was code-path pruning. Previously Mix only added entries to the load paths, so compiling the 21st dependency meant searching a code path with all 20 earlier ones, slowing things down. Elixir 1.15 prunes the code path to only the listed dependencies, bringing behavior closer to a mix release. Combined with Erlang/OTP 26's concurrent application startup and cached lookups, the team benchmarked Livebook seeing roughly 16% faster compilation and 30% faster boot times, with some reports of up to 40% faster compilation.

Better compiler feedback

The compiler can now emit many errors for a single file instead of aborting at the first one, giving developers more feedback per run. A new Code.with_diagnostics/2 function lets editors surface several errors at once, laying groundwork for richer diagnostics in later releases.

Erlang logger integration

Elixir 1.15 completed integration with the Erlang/OTP logger, adding global logger metadata and file logging with rotation and compression out of the box. It soft-deprecated Elixir's own Logger Backends in favor of Erlang's Logger handlers, automatically translating existing :console backend configuration to the new default handler and formatter.

Related on Skillo

See also: Elixir 1.14 and the dbg macro, Elixir 1.16's compiler diagnostics.

Sources

• Elixir v1.15 released (elixir-lang.org)

Published date reflects the original event date (2023-06-19). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.