I used this program to acquire some data and record down to a file. For your information, the file size in the end of the program is about 100kB. But, the system memory used by Labview is consumed 20MB more in the end than in the begining of the program and obviously it takes much longer to get one single data. I initially thought that is because I used loops and the size of the resulting arrays become larger, however I used indicators to check the size, which doesn't change much. Is that because Labview never free up the memory used in one program? And has anyone met that program?