How compare my code? (Testing)

i have a graph partitioning algorithm code , i did some test on code, and i get execution time ex: for 100 node execution time: 5.10s . now i have a graph (node- execution time) , but to improve the code , i want to compare .

for example my code 100 node, 5.10s other optimal : 100 node 4.0s

i can say "yes i have to improve my code my time is not good enough" .

my question is how can i do that comparison .

(if i am not clear enough i am sorry, I will getting better the question from feedbacks)