Reply to Lag with traktor s2 while playing two tracks at once.. why?

So i just purchased a brand new macbook pro in december, along with traktor s2 which includes traktor pro 2.

When i first played with it, id have two tracks playing side by side. No problem.


After a couple months go by, i download some more applications for my macbook, now it seems like i can't play two tracks at the same time without it lagging.

The demo tracks play fine together, when its same time.

But when i try and play two different tracks that i download from sound cloud, it never works, just starts to lag.

Then i try 1 track from sound cloud and demo track thats included with the traktor software, still lags.

Does this happen to anybody else? I don't know why this would be happening. I haven't experienced this problem before, just happened all of a sudden, do i need to download something from NI website? Like a update or patch?

I bought this mbp from guitar center along with s2 all in same day, and they said it would run traktor fine. Not sure if its my computer or maybe my settings in trakto? is there any settings in traktor that could cause the two tracks not being able to play side by side at the same time?

They are long tracks from sound cloud.com one is 62 minutes the other is 102 minutes long.
Which in my mind aren't that long and should have this problem, when people have 6 hour long mixes up on sound cloud.

I don't know why this is happening all of a sudden and it bothers me that the track B is like glitching, laggin. It can't play smoothly.