diff --git a/Cargo.toml b/Cargo.toml
index 3f7f41e48..29d4701a0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -112,6 +112,12 @@ zstd = "0.12.4"
 jj-lib = { path = "lib", version = "0.14.0" }
 testutils = { path = "lib/testutils" }
 
+# Insta suggests compiling these packages in opt mode for faster testing.
+# See https://docs.rs/insta/latest/insta/#optional-faster-runs.
+[profile.dev.package]
+insta.opt-level = 3
+similar.opt-level = 3
+
 [profile.release]
 strip = "debuginfo"
 codegen-units = 1