--- title: "Improving the performance of the popular Clojure development tool clojure-lsp" url: https://daily.dev/posts/improving-the-performance-of-the-popular-clojure-development-tool-clojure-lsp-uu4asgzf1 source_url: https://www.metabase.com/blog/improving-performance-clojure-development-tools type: article source: "Metabase" published: 2026-05-12T18:24:13.983Z updated: 2026-05-12T18:24:44.316Z tags: ["performance", "clojure"] reading_time: 9 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Improving the performance of the popular Clojure development tool clojure-lsp **[Metabase](https://daily.dev/sources/metabase)** · 9 min read · 0 upvotes · 0 comments ## Summary A Metabase engineer investigated why clojure-lsp took over 3 minutes to analyze the Metabase codebase. Using VisualVM and clj-async-profiler allocation profiling, they identified key bottlenecks in clj-kondo (which accounts for 95% of initialization work). Optimizations included: improving the deep-merge function to skip unnecessary assoc operations, removing a dynamic variable on a hot path in rewrite-clj, and replacing clojure.core/memoize with a specialized implementation using nested maps for two-argument functions. The result was a 2x reduction in startup time and nearly 3x reduction in heap allocations (from 145GB to 51.6GB total allocated). Changes are merged and will ship in the next clojure-lsp release. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Clojure is almost as fast as C \(with some help\)](https://daily.dev/posts/clojure-is-almost-as-fast-as-c-with-some-help--faibfofkn) · Lobsters · 0 upvotes · 0 comments - [Bringing Clojure programming to Enterprise](https://daily.dev/posts/bringing-clojure-programming-to-enterprise-xmingfzvs) · Hacker News · 0 upvotes · 0 comments - [jank now has its own custom IR](https://daily.dev/posts/jank-now-has-its-own-custom-ir-xb0nzvh5o) · Lobsters · 0 upvotes · 0 comments --- Tags: [#performance](https://daily.dev/tags/performance), [#clojure](https://daily.dev/tags/clojure) [View this post on daily.dev](https://daily.dev/posts/improving-the-performance-of-the-popular-clojure-development-tool-clojure-lsp-uu4asgzf1)