optimize by default

Makefile

@@ -8,7 +8,7 @@ HDRS = \
 	src/toolchain.h
 BUILD = build
 OBJS = $(patsubst %,$(BUILD)/%.o,$(SRCS))
-CFLAGS = -g -Wall -Wextra -Wno-unused-parameter
+CFLAGS = -g -O3 -Wall -Wextra -Wno-unused-parameter
 LDLIBS = -lpthread
 
 $(BUILD)/%.cc.o: %.cc $(HDRS)