Optimization Advice for beginer?

I am in a second level college programing class, and we have to make a maze solving program, and we are graded on how much time out program uses to produce a optimal solution.  I have done just about everything I can to optimize my code, my program takes  0.055 seconds to complete all of the test cases, but I need to run a little faster.

 I was wondering if you know any good optimization flags that I can use that would increase perfomance. I am using stack and queue data strutures. Also, I do not know what type of machine, or "Autograder" will compile and grade my code, but I am allowed to submit my own makefile.

Here is my current make file:

"


.SUFFIXES: .o .cpp

OBJS = prog.o maize.o
#CC = g++ -Wall
#CC = g++ -g -Wall
CC = g++ -O3 -Wall -O -funroll-loops
AR       = ar cr

all : $(OBJS) UTIL/libutil.a
        $(CC) -o MortimerMaze $(OBJS) UTIL/libutil.a

UTIL/libutil.a:
        cd $(PWD)/UTIL; make PWD=$(PWD)/UTIL

clean:
        rm -rf *.o MortimerMaze
        cd $(PWD)/UTIL; make PWD=$(PWD)/UTIL clean

.cpp.o:
        $(CC) -c $*.cpp
       
         
"