I hope I can use my poor English to understand what we tell you and ppy problems encountered
First, plz remember:
1.when we encountered a LAG, we have reduced the system processes as much as possible
2.Even did a client only store one song
3.This is not an individual problem, I have encountered at least 10 people appeared in this issue
OK,Our problems is: instant LAG
Can be understood as fps dropped in a flash,When viewing the Task Manager, you can see the CPU at that moment a sudden increase occupancy
Of course, this is just a moment, about 0.1-0.3 seconds, fps back to normal, CPU returned to normal occupancy
In the long suffering, I found a rule
Each LAG will appear in a fixed time
I did a lot of try, test out the time of the first LAG appears at about 1:36
Of course, this is the time game time rather than song time
So I guess the first time LAG from loading the game until the moment of 100 secondslike this:

Why is GAME TIME:
If you select the 1 minute 50 seconds of the song, coupled with DT, it will not appear LAG
If you have time in the game to be pause in about 1:20,and wait 20 seconds, it will not appear LAG(but in this 20 seconds will appear lag,But it will not affect the actual game)
Therefore, the second time is fixed LAG
Although I have no energy to do another experiment, but can understand a little more than 3 minutes in the office
may be is 200 seconds :O
Well, now the important thing finished,
I talk about my situation encountered:
After the great start the game very smooth about 30 minutes
About 30 minutes later, when I choose a song, playing to a 100 second place, the mouse will LAG the moment (if CTB, is the key to LAG), if the song more than 3 minutes, also at the event in 200 seconds To the 2nd moment of LAG
Each song will be chosen in such a problem, unless the actual game time of less than 100 seconds
The beginning is a very short experience of the moment, when continuing the game down (do not turn off or restart the game), LAG will be growing, even up to 0.5 seconds
If you restart the game, as if the load is cleared of the same
Re-time 30 minutes
PC Information:
CPU:8750
GPU:7900GTO
HD:7200rpm 500Gb
Memory:DDR2 1066 2G
Game:
OpenGL: ×
DirectX: √
Limited: all try
resolution: 1024x768/800x600
fullcreen: ×
settings: low-end PC