diff --git a/CHANGELOG.md b/CHANGELOG.md
index b3835db..1ca4ac8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,27 @@ History note:
 - Entries below are synchronized and curated for `1.5.x`.
 - Earlier history may be incomplete and should be cross-checked with git tags/commits when needed.
 
+## 1.5.4 (2026-04-03)
+
+### Runtime and compiler stability
+- Stabilized the recent `piSpigot` benchmark/compiler work for release.
+- Fixed numeric-mix regressions introduced by overly broad int-coercion in bytecode compilation.
+- Restored correct behavior for decimal arithmetic, mixed real/int flows, list literals, list size checks, and national-character script cases.
+- Fixed plain-list index fast paths so they no longer bypass subclass behavior such as `ObservableList` hooks and flow notifications.
+- Hardened local numeric compare fast paths to correctly handle primitive-coded frame slots.
+
+### Performance and examples
+- Added `piSpigot` benchmark/example coverage:
+  - `examples/pi-test.lyng`
+  - `examples/pi-bench.lyng`
+  - JVM benchmark test for release-baseline verification
+- Kept the safe list/index/runtime wins that improve the optimized `piSpigot` path without reintroducing type-unsound coercions.
+- Changed the default `RVAL_FASTPATH` setting off on JVM/Android and in the benchmark preset after verification that it no longer helps the stabilized `piSpigot` workload.
+
+### Release notes
+- Full JVM and wasm test gates pass on the release tree.
+- Benchmark findings and remaining post-release optimization targets are documented in `notes/pi_spigot_benchmark_baseline_2026-04-03.md`.
+
 ## 1.5.1 (2026-03-25)
 
 ### Language
diff --git a/lynglib/build.gradle.kts b/lynglib/build.gradle.kts
index 7289dac..fe1b836 100644
--- a/lynglib/build.gradle.kts
+++ b/lynglib/build.gradle.kts
@@ -21,7 +21,7 @@ import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
 import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 
 group = "net.sergeych"
-version = "1.5.4-SNAPSHOT"
+version = "1.5.4"
 
 // Removed legacy buildscript classpath declarations; plugins are applied via the plugins DSL below
 
diff --git a/lynglib/src/androidMain/kotlin/net/sergeych/lyng/PerfDefaults.android.kt b/lynglib/src/androidMain/kotlin/net/sergeych/lyng/PerfDefaults.android.kt
index e15992f..beb252a 100644
--- a/lynglib/src/androidMain/kotlin/net/sergeych/lyng/PerfDefaults.android.kt
+++ b/lynglib/src/androidMain/kotlin/net/sergeych/lyng/PerfDefaults.android.kt
@@ -36,7 +36,7 @@ actual object PerfDefaults {
     actual val PIC_DEBUG_COUNTERS: Boolean = false
 
     actual val PRIMITIVE_FASTOPS: Boolean = true
-    actual val RVAL_FASTPATH: Boolean = true
+    actual val RVAL_FASTPATH: Boolean = false
     // Regex caching aligns with JVM behavior on Android (Dalvik/ART)
     actual val REGEX_CACHE: Boolean = true
     actual val ARG_SMALL_ARITY_12: Boolean = false
diff --git a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/PerfProfiles.kt b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/PerfProfiles.kt
index 19276a9..b1bcaf4 100644
--- a/lynglib/src/commonMain/kotlin/net/sergeych/lyng/PerfProfiles.kt
+++ b/lynglib/src/commonMain/kotlin/net/sergeych/lyng/PerfProfiles.kt
@@ -180,7 +180,7 @@ object PerfProfiles {
         PerfFlags.PIC_DEBUG_COUNTERS = false
 
         PerfFlags.PRIMITIVE_FASTOPS = true
-        PerfFlags.RVAL_FASTPATH = true
+        PerfFlags.RVAL_FASTPATH = false
 
         // Keep regex cache/platform setting; enable on JVM typically
         PerfFlags.REGEX_CACHE = PerfDefaults.REGEX_CACHE
diff --git a/lynglib/src/jvmMain/kotlin/net/sergeych/lyng/PerfDefaults.jvm.kt b/lynglib/src/jvmMain/kotlin/net/sergeych/lyng/PerfDefaults.jvm.kt
index 60078ee..ed271e5 100644
--- a/lynglib/src/jvmMain/kotlin/net/sergeych/lyng/PerfDefaults.jvm.kt
+++ b/lynglib/src/jvmMain/kotlin/net/sergeych/lyng/PerfDefaults.jvm.kt
@@ -36,7 +36,7 @@ actual object PerfDefaults {
     actual val PIC_DEBUG_COUNTERS: Boolean = false
 
     actual val PRIMITIVE_FASTOPS: Boolean = true
-    actual val RVAL_FASTPATH: Boolean = true
+    actual val RVAL_FASTPATH: Boolean = false
 
     // Regex caching (JVM-first): enabled by default on JVM
     actual val REGEX_CACHE: Boolean = true