diff --git a/packages/openjphjs/CMakeLists.txt b/packages/openjphjs/CMakeLists.txt
index b3a1b03..c4e3f5e 100644
--- a/packages/openjphjs/CMakeLists.txt
+++ b/packages/openjphjs/CMakeLists.txt
@@ -15,7 +15,13 @@ if(NOT EXISTS "${PROJECT_SOURCE_DIR}/extern/openjph/CMakeLists.txt")
 endif()
 
 if(EMSCRIPTEN)
-  option(OJPH_DISABLE_INTEL_SIMD "Disables the use of SIMD instructions and associated files" ON)
+  # OpenJPH 0.30.1 builds WASM SIMD by default (OJPH_DISABLE_SIMD=OFF) and emits
+  # -msimd128 + the *_wasm.cpp kernels. Do NOT set the deprecated
+  # OJPH_DISABLE_INTEL_SIMD: 0.30.1 bridges it onto OJPH_DISABLE_SIMD
+  # (extern/openjph/CMakeLists.txt), so the old "=ON" — which used to mean
+  # "skip Intel SIMD, use the WASM path" — now disables ALL SIMD and ships a
+  # ~2x-slower scalar wasm. Keep SIMD explicitly enabled.
+  set(OJPH_DISABLE_SIMD OFF CACHE BOOL "Enable OpenJPH WASM SIMD" FORCE)
 endif()
 
 option(BUILD_SHARED_LIBS "" OFF)
diff --git a/packages/openjphjs/build.sh b/packages/openjphjs/build.sh
index 52d23ab..6cfa1ee 100755
--- a/packages/openjphjs/build.sh
+++ b/packages/openjphjs/build.sh
@@ -1,8 +1,11 @@
 #!/bin/sh
 mkdir -p build
 mkdir -p dist
-(cd build && CXXFLAGS=-msimd128 emcmake cmake -DCMAKE_BUILD_TYPE=Debug ..)
-#(cd build && CXXFLAGS=-msimd128 emcmake cmake ..)
+(cd build && CXXFLAGS=-msimd128 emcmake cmake -DCMAKE_BUILD_TYPE=Release ..)
+# NOTE: this shipped a Debug (-O0) wasm until now, which left the SIMD kernels
+# unoptimized (SIMD intrinsics not inlined) — making decode/encode far slower
+# and the binary far larger than they should be. Release (-O3) is the correct
+# artifact for a published codec.
 (cd build && emmake make VERBOSE=1 -j ${nprocs})
 cp ./build/src/openjphjs.js ./dist
 cp ./build/src/openjphjs.wasm ./dist
diff --git a/packages/openjphjs/extern/openjph b/packages/openjphjs/extern/openjph
index e01c7b7..0748112 160000
--- a/packages/openjphjs/extern/openjph
+++ b/packages/openjphjs/extern/openjph
@@ -1 +1 @@
-Subproject commit e01c7b7f9e7ecbb15cf13bb45661c9a41ab7fec6
+Subproject commit 0748112be8820ce97a4ea3e576bd817c804737d5
diff --git a/packages/openjphjs/src/CMakeLists.txt b/packages/openjphjs/src/CMakeLists.txt
index 83a9abe..42e31f2 100644
--- a/packages/openjphjs/src/CMakeLists.txt
+++ b/packages/openjphjs/src/CMakeLists.txt
@@ -1,7 +1,17 @@
 
 add_executable(openjphjs jslib.cpp)
 
-target_link_libraries(openjphjs PRIVATE openjphsimd)
+# OpenJPH 0.30.1 builds a single `openjph` library (SIMD is folded in,
+# architecture-agnostic); the old separate `openjphsimd` target no longer
+# exists. Upstream's own wasm wrapper links `openjph` too.
+target_link_libraries(openjphjs PRIVATE openjph)
+# OpenJPH 0.30.1 moved its public headers under src/core/openjph (and
+# src/core/shared); older releases exposed them on a flatter include path, so
+# our bare `#include <ojph_arch.h>` no longer resolves via the linked target
+# alone. Add the 0.30.1 header roots explicitly.
+target_include_directories(openjphjs PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/../extern/openjph/src/core/openjph
+    ${CMAKE_CURRENT_SOURCE_DIR}/../extern/openjph/src/core/shared)
 target_compile_options(openjphjs PRIVATE -DOJPH_ENABLE_WASM_SIMD -msimd128)
 target_compile_features(openjphjs PUBLIC cxx_std_11)
 set_target_properties(