diff --git a/default.nix b/default.nix
index df894c39c76..9b5bba68d5b 100644
--- a/default.nix
+++ b/default.nix
@@ -85,6 +85,7 @@ let
     wasmtime
     rust-bindgen
     python3
+    binaryen
   ] ++ pkgs.lib.optional pkgs.stdenv.isDarwin [
     libiconv
   ];
diff --git a/rts/Makefile b/rts/Makefile
index 2d6578c1171..cd825f7d9a3 100644
--- a/rts/Makefile
+++ b/rts/Makefile
@@ -3,6 +3,7 @@ SHELL:=bash -O globstar
 CLANG ?= clang-18
 WASM_CLANG ?= clang-18
 WASM_LD ?= wasm-ld-18
+WASM_OPT = wasm-opt
 
 #
 # We manually list all the .c files of libtommath that we care about.
@@ -151,7 +152,7 @@ RTS_LL_64=$(CLANG) -cc1 -triple wasm64-unknown-emscripten -emit-obj \
 	-mllvm -enable-emscripten-sjlj -mllvm -disable-lsr \
 	-Wno-override-module
 RTS_LL_64_DEBUG=$(RTS_LL_64)
-RTS_LL_64_RELEASE=$(RTS_LL_64) -O2
+RTS_LL_64_RELEASE=$(RTS_LL_64) -Oz
 
 #
 # Let make automatically search these directories (tommath and musl) for .c files
@@ -266,7 +267,7 @@ $(TOMMATH_BINDINGS_RS_64): | _build/wasm64
 RTS_DEPENDENCIES_32=$(TOMMATH_BINDINGS_RS_32) $(RTS_RUST_FILES) $(RTS_CARGO_FILES) | _build/wasm32
 RTS_BUILD_32=cd motoko-rts && cargo build --target=wasm32-unknown-emscripten -Zbuild-std=core,alloc
 RTS_DEBUG_BUILD_32=$(RTS_BUILD_32)
-RTS_RELEASE_BUILD_32=$(RTS_BUILD_32) --release
+RTS_RELEASE_BUILD_32=$(RTS_BUILD_32) --release -Zbuild-std-features="panic_immediate_abort,optimize_for_size"
 RTS_DEBUG_TARGET_32=motoko-rts/target/wasm32-unknown-emscripten/debug/libmotoko_rts.a
 RTS_RELEASE_TARGET_32=motoko-rts/target/wasm32-unknown-emscripten/release/libmotoko_rts.a
 
@@ -298,7 +299,7 @@ RTS_DEPENDENCIES_64=$(TOMMATH_BINDINGS_RS_64) $(RTS_RUST_FILES) $(RTS_CARGO_FILE
 COMPILER_FLAGS_64=--emit=llvm-ir
 RTS_BUILD_64=cd motoko-rts && RUSTFLAGS="${COMPILER_FLAGS_64}" cargo build --target=wasm64-unknown-unknown -Zbuild-std=core,alloc --features enhanced_orthogonal_persistence
 RTS_DEBUG_BUILD_64=$(RTS_BUILD_64)
-RTS_RELEASE_BUILD_64=$(RTS_BUILD_64) --release
+RTS_RELEASE_BUILD_64=$(RTS_BUILD_64) --release -Zbuild-std-features="panic_immediate_abort,optimize_for_size"
 
 RTS_DEBUG_TARGET_64_FOLDER=motoko-rts/target/wasm64-unknown-unknown/debug
 RTS_RELEASE_TARGET_64_FOLDER=motoko-rts/target/wasm64-unknown-unknown/release
@@ -444,11 +445,13 @@ LINKER_OPTIONS_64=\
   $(EXPORTED_SYMBOLS:%=--export=%) \
   --whole-archive --experimental-pic
 
+WASM_OPT_OPTIONS=-Oz
 
 mo-rts-non-incremental.wasm: $(RTS_RUST_NON_INCREMENTAL_WASM_32_A) $(WASM_A_DEPENDENCIES_32)
 	$(WASM_LD) -o $@ \
 		$(LINKER_OPTIONS_32) \
 		$+
+	$(WASM_OPT) $(WASM_OPT_OPTIONS) -o $@ $@
 
 mo-rts-non-incremental-debug.wasm: $(RTS_RUST_NON_INCREMENTAL_DEBUG_WASM_32_A) $(WASM_A_DEPENDENCIES_32)
 	$(WASM_LD) -o $@ \
@@ -459,6 +462,7 @@ mo-rts-incremental.wasm: $(RTS_RUST_INCREMENTAL_WASM_32_A) $(WASM_A_DEPENDENCIES
 	$(WASM_LD) -o $@ \
 		$(LINKER_OPTIONS_32) \
 		$+
+	$(WASM_OPT) $(WASM_OPT_OPTIONS) -o $@ $@
 
 mo-rts-incremental-debug.wasm: $(RTS_RUST_INCREMENTAL_DEBUG_WASM_32_A) $(WASM_A_DEPENDENCIES_32)
 	$(WASM_LD) -o $@ \
@@ -469,6 +473,7 @@ mo-rts-eop.wasm: $(RTS_RUST_WASM_64_A) $(CORE_WASM_64_A) $(ALLOC_WASM_64_A) $(CO
 	$(WASM_LD) -o $@ \
 		$(LINKER_OPTIONS_64) \
 		$+
+	$(WASM_OPT) $(WASM_OPT_OPTIONS) -o $@ $@
 
 mo-rts-eop-debug.wasm: $(RTS_RUST_DEBUG_WASM_64_A) $(CORE_DEBUG_WASM_64_A) $(ALLOC_DEBUG_WASM_64_A) $(COMPILER_BUILTINS_DEBUG_WASM_64_A) $(WASM_A_DEPENDENCIES_64)
 	$(WASM_LD) -o $@ \
diff --git a/rts/motoko-rts/Cargo.toml b/rts/motoko-rts/Cargo.toml
index 1e29a0b5cd0..09f39072345 100644
--- a/rts/motoko-rts/Cargo.toml
+++ b/rts/motoko-rts/Cargo.toml
@@ -44,4 +44,4 @@ panic = "abort"
 [profile.release]
 panic = "abort"
 codegen-units = 1 # makes debugging easier
-opt-level = "s" # optimize for size
+opt-level = "z" # super-optimize for size
diff --git a/test/bench/ok/alloc.drun-run.ok b/test/bench/ok/alloc.drun-run.ok
index f4ae3aa77a9..87a3330c319 100644
--- a/test/bench/ok/alloc.drun-run.ok
+++ b/test/bench/ok/alloc.drun-run.ok
@@ -1,8 +1,8 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: (+268_435_456, 3_071_963_514)
+debug.print: (+268_435_456, 3_071_992_198)
 ingress Completed: Reply: 0x4449444c0000
-debug.print: (+268_435_456, 3_070_505_338)
+debug.print: (+268_435_456, 3_070_534_022)
 ingress Completed: Reply: 0x4449444c0000
-debug.print: (+268_435_456, 3_070_505_338)
+debug.print: (+268_435_456, 3_070_534_022)
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/bignum.drun-run.ok b/test/bench/ok/bignum.drun-run.ok
index a883c928749..8ed960768d8 100644
--- a/test/bench/ok/bignum.drun-run.ok
+++ b/test/bench/ok/bignum.drun-run.ok
@@ -1,6 +1,6 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: {cycles = 2_467_268; size = +59_652}
+debug.print: {cycles = 2_508_947; size = +59_652}
 ingress Completed: Reply: 0x4449444c0000
-debug.print: {cycles = 105_698_659; size = +1_817_872}
+debug.print: {cycles = 105_771_400; size = +1_817_872}
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/candid-subtype-cost.drun-run.ok b/test/bench/ok/candid-subtype-cost.drun-run.ok
index 92c75d49179..c2d69ad296f 100644
--- a/test/bench/ok/candid-subtype-cost.drun-run.ok
+++ b/test/bench/ok/candid-subtype-cost.drun-run.ok
@@ -1,4 +1,4 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: {cycles = 941_951; heap_bytes = +12_564}
+debug.print: {cycles = 1_035_990; heap_bytes = +12_564}
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/heap-32.drun-run.ok b/test/bench/ok/heap-32.drun-run.ok
index 9eaf86b3290..2635bb3a87c 100644
--- a/test/bench/ok/heap-32.drun-run.ok
+++ b/test/bench/ok/heap-32.drun-run.ok
@@ -1,5 +1,5 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: (50_227, +29_863_068, 739_048_937)
-debug.print: (50_070, +32_992_212, 803_211_842)
+debug.print: (50_227, +29_863_068, 683_152_487)
+debug.print: (50_070, +32_992_212, 742_929_436)
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/heap-64.drun-run.ok b/test/bench/ok/heap-64.drun-run.ok
index fb2db91dfd5..16bebcce5ee 100644
--- a/test/bench/ok/heap-64.drun-run.ok
+++ b/test/bench/ok/heap-64.drun-run.ok
@@ -1,5 +1,5 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: (49_965, +47_942_744, 997_701_676)
-debug.print: (49_806, +47_960_000, 1_006_736_486)
+debug.print: (49_965, +47_942_744, 936_552_826)
+debug.print: (49_806, +47_960_000, 944_655_592)
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/nat16.drun-run.ok b/test/bench/ok/nat16.drun-run.ok
index 8febef52370..030796b7bef 100644
--- a/test/bench/ok/nat16.drun-run.ok
+++ b/test/bench/ok/nat16.drun-run.ok
@@ -1,4 +1,4 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: (0, 51_380_880)
+debug.print: (0, 51_380_892)
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/palindrome.drun-run.ok b/test/bench/ok/palindrome.drun-run.ok
index c4cbbeed192..53b2cdf7d0e 100644
--- a/test/bench/ok/palindrome.drun-run.ok
+++ b/test/bench/ok/palindrome.drun-run.ok
@@ -1,9 +1,9 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: (true, +1_188, 13_158)
-debug.print: (false, +1_188, 12_207)
-debug.print: (false, +1_188, 13_137)
-debug.print: (true, +868, 13_266)
-debug.print: (false, +868, 11_729)
-debug.print: (false, +868, 13_214)
+debug.print: (true, +1_188, 13_503)
+debug.print: (false, +1_188, 12_552)
+debug.print: (false, +1_188, 13_482)
+debug.print: (true, +868, 13_611)
+debug.print: (false, +868, 12_074)
+debug.print: (false, +868, 13_559)
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/region-mem.drun-run.ok b/test/bench/ok/region-mem.drun-run.ok
index efb2339ece9..8f9500fac01 100644
--- a/test/bench/ok/region-mem.drun-run.ok
+++ b/test/bench/ok/region-mem.drun-run.ok
@@ -1,4 +1,4 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: {heap_diff = 0; instr_diff = 5_939_134_825}
+debug.print: {heap_diff = 0; instr_diff = 9_235_857_781}
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/region0-mem.drun-run.ok b/test/bench/ok/region0-mem.drun-run.ok
index 8b763c2ea6f..5f25086b4e5 100644
--- a/test/bench/ok/region0-mem.drun-run.ok
+++ b/test/bench/ok/region0-mem.drun-run.ok
@@ -1,4 +1,4 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: {heap_diff = 0; instr_diff = 6_366_953_833}
+debug.print: {heap_diff = 0; instr_diff = 9_663_676_789}
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/bench/ok/stable-mem.drun-run.ok b/test/bench/ok/stable-mem.drun-run.ok
index 5e3eeec3bce..69f23a6f184 100644
--- a/test/bench/ok/stable-mem.drun-run.ok
+++ b/test/bench/ok/stable-mem.drun-run.ok
@@ -1,4 +1,4 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: {heap_diff = 0; instr_diff = 3_875_537_257}
+debug.print: {heap_diff = 0; instr_diff = 3_875_537_269}
 ingress Completed: Reply: 0x4449444c0000
diff --git a/test/run-drun/empty-actor-classical.mo b/test/run-drun/empty-actor-classical.mo
index 3343abea28a..008e213b504 100644
--- a/test/run-drun/empty-actor-classical.mo
+++ b/test/run-drun/empty-actor-classical.mo
@@ -2,6 +2,4 @@
 actor {};
 
 // CHECK:  (func $canister_init
-// CHECK:    call ${{copying_gc|compacting_gc|generational_gc|incremental_gc}}
-
 // CHECK:  (export "canister_init" (func $canister_init))
diff --git a/test/run-drun/empty-actor-enhanced.mo b/test/run-drun/empty-actor-enhanced.mo
index b5be96391ef..fbc815c9754 100644
--- a/test/run-drun/empty-actor-enhanced.mo
+++ b/test/run-drun/empty-actor-enhanced.mo
@@ -2,14 +2,9 @@
 actor {};
 
 // CHECK:  (func $@motoko_async_destabilization (type 0)
-// CHECK:         call $trans_state10 
-// CHECK:         call $post_exp
-// CHECK:         call $start_gc_after_destabilization
-// CHECK:         call $trans_state4
 // CHECK:         call $@initialize_main_actor
 
 // CHECK:  (func $canister_init
-// CHECK-NEXT:    call $trans_state
-// CHECK-NEXT:    call $init
+// CHECK:         call $init
 
 // CHECK:  (export "canister_init" (func $canister_init))