diff -up thunderbird-45.3.0/mozilla/configure.in.no_Os thunderbird-45.3.0/mozilla/configure.in --- thunderbird-45.3.0/mozilla/configure.in.no_Os 2016-08-30 16:29:23.611672500 +0200 +++ thunderbird-45.3.0/mozilla/configure.in 2016-08-30 16:29:51.520620404 +0200 @@ -2115,7 +2115,7 @@ ia64*-hpux*) MOZ_OPTIMIZE_FLAGS="-O2" elif test "$GNU_CC" -o "$GNU_CXX"; then MOZ_PGO_OPTIMIZE_FLAGS="-O3" - MOZ_OPTIMIZE_FLAGS="-Os" + MOZ_OPTIMIZE_FLAGS="" if test -z "$CLANG_CC"; then MOZ_OPTIMIZE_FLAGS="-freorder-blocks $MOZ_OPTIMIZE_FLAGS" fi