Update Make with -O2 flag

Makefile

@@ -2,7 +2,7 @@ CC = gcc
 IDIR = include
 ODIR = obj
 SRC = src
-CFLAGS = -I include -I ~/.local/include -L ~/.local/lib -L ~/.local/lib64
+CFLAGS = -O2 -I include -I ~/.local/include -L ~/.local/lib -L ~/.local/lib64
 LIBS = -lhts -lpthread
 DEPS = $(IDIR)/functions.h
 OBJ = $(ODIR)/functions.o $(ODIR)/main.o