I'm having a strange problem when reading data from a file into memory using LabVIEW's "Read from SGL file" VI and a bunch of array operations (Initialise, Replace Subset). The read operation is run many thousands of times, as it resides inside two nested For Loops.
Without any outside intervention, the process takes quite a while to complete (a few minutes), although when all the data's been read it doesn't take up that much memory. However, while I had some probe windows open on a completely different part of the program, I noticed that the speed became inexplicably much faster while the probe window was being moved. In fact, it happens when I click and hold the mouse button on the border of the probe window, I don't have to move it at all. The probe window doesn't have to be probing a point in a currently running SubVI.
Left to its own devices, the process takes about 10 minutes, during which time it uses about 3% of the processor time. With a probe window focussed, it completes the process in about 20 seconds and uses about 50% CPU. Fiddling with the process priority for LabVIEW.exe seems to have no effect.
LabVIEW 7.1, WinXP SP1 running on a 3GHz Hyperthreading P4 with 512MB RAM.
Any ideas?
