diff -up mozilla-release/js/src/configure.in.opt mozilla-release/js/src/configure.in
--- mozilla-release/js/src/configure.in.opt	2015-05-04 02:43:23.000000000 +0200
+++ mozilla-release/js/src/configure.in	2015-05-07 14:21:07.685405039 +0200
@@ -1492,7 +1492,7 @@ case "$host" in
 *-linux*|*-kfreebsd*-gnu|*-gnu*)
     HOST_CFLAGS="$HOST_CFLAGS -DXP_UNIX"
     HOST_NSPR_MDCPUCFG='\"md/_linux.cfg\"'
-    HOST_OPTIMIZE_FLAGS="${HOST_OPTIMIZE_FLAGS=-O3}"
+    HOST_OPTIMIZE_FLAGS="${HOST_OPTIMIZE_FLAGS=-O1}"
     ;;
 
 *)
@@ -1674,8 +1674,8 @@ ia64*-hpux*)
         # while; Intel recommends against using it.
         MOZ_OPTIMIZE_FLAGS="-O2"
     elif test "$GNU_CC" -o "$GNU_CXX"; then
-        MOZ_PGO_OPTIMIZE_FLAGS="-O3"
-        MOZ_OPTIMIZE_FLAGS="-O3"
+        MOZ_PGO_OPTIMIZE_FLAGS="-O1"
+        MOZ_OPTIMIZE_FLAGS="-O1"
         if test -z "$CLANG_CC"; then
            MOZ_OPTIMIZE_FLAGS="-freorder-blocks $MOZ_OPTIMIZE_FLAGS"
         fi