diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index aa5f0b7..7103dbf 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -824,7 +824,7 @@
     # full minus MBEDTLS_USE_PSA_CRYPTO: run the same set of tests as basic-build-test.sh
     msg "build: cmake, full config + MBEDTLS_USE_PSA_CRYPTO, ASan"
     scripts/config.pl full
-    scripts/config.pl unset MBEDTLS_MEMORY_BACKTRACE # too slow for tests
+    scripts/config.pl unset MBEDTLS_MEMORY_BUFFER_ALLOC_C # slow and makes ASan mostly ineffective
     scripts/config.pl set MBEDTLS_ECP_RESTARTABLE  # not using PSA, so enable restartable ECC
     scripts/config.pl set MBEDTLS_PSA_CRYPTO_C
     scripts/config.pl unset MBEDTLS_USE_PSA_CRYPTO
@@ -1035,6 +1035,7 @@
     # Build once with -O0, to compile out the i386 specific inline assembly
     msg "build: i386, make, gcc -O0 (ASan build)" # ~ 30s
     scripts/config.pl full
+    scripts/config.pl unset MBEDTLS_MEMORY_BUFFER_ALLOC_C # slow and makes ASan mostly ineffective
     make CC=gcc CFLAGS='-O0 -Werror -Wall -Wextra -m32 -fsanitize=address' LDFLAGS='-m32 -fsanitize=address'
 
     msg "test: i386, make, gcc -O0 (ASan build)"
@@ -1051,7 +1052,7 @@
     # Build again with -O1, to compile in the i386 specific inline assembly
     msg "build: i386, make, gcc -O1 (ASan build)" # ~ 30s
     scripts/config.pl full
-    scripts/config.pl unset MBEDTLS_MEMORY_BUFFER_ALLOC_C
+    scripts/config.pl unset MBEDTLS_MEMORY_BUFFER_ALLOC_C # slow and makes ASan mostly ineffective
     make CC=gcc CFLAGS='-O1 -Werror -Wall -Wextra -m32 -fsanitize=address' LDFLAGS='-m32 -fsanitize=address'
 
     msg "test: i386, make, gcc -O1 (ASan build)"