--- a/configure.in
+++ b/configure.in
@@ -193,28 +193,6 @@
 # Byte order
 AC_C_BIGENDIAN(MYCPPFLAGS="$MYCPPFLAGS -D_MYBIGEND")
 
-# System-depending optimization
-printf 'checking for 64-bit availability... '
-if printf 'main() {}' | $CC -xc -m64 -o config.tmp - >config.tmp 2>&1
-then
-  MYCFLAGS="-m64 $MYCFLAGS"
-  MYCXXFLAGS="-m64 $MYCXXFLAGS"
-  printf 'yes\n'
-else
-  printf 'no\n'
-fi
-if test "$enable_opt" != "no"
-then
-  printf 'checking for CPU optimization availability... '
-  if printf 'main() {}' | $CC -xc -march=native -o config.tmp - >config.tmp 2>&1
-  then
-    MYCFLAGS="-march=native $MYCFLAGS"
-    MYCXXFLAGS="-march=native $MYCXXFLAGS"
-    printf 'yes\n'
-  else
-    printf 'no\n'
-  fi
-fi
 printf 'checking for useless warnings... '
 if printf 'main() {}' | $CC -xc \
   -Wno-unused-but-set-variable -Wno-unused-but-set-parameter -o config.tmp - >config.tmp 2>&1