The game lags even though it uses only 40% used memory and 60% allocated memory

[xXfirelightXx]

my attack of the bteam is fked up because while using the optifine mod trying to reduce the lag it was showing me that I only use 40 of the used memory and 60 of the allocated memory I dont know what the problem is but the lag is so bad that i only get 1-0 frames per second P.S. An even stranger thing is that when I go into settings my frames go up to 40-50 someone please help me I cant do anything even after restarting and re-downloading attack of the b team

[Kalbintion]

http://forums.technicpack.net/tracker/issue-3190-im-getting-1-0-frames-per-second-even-though-atbt-only-uses-40-used-memory-and-60-allocated-memory/