TDMS Opens Slowly

[Matt_W1]

My understanding is when you open a tdms file it verifies the index, or recreates it if it's missing. So the more fragmented the file the bigger the index and the more slow IO needed to verify/recreate it.

[YongqingYe]

I can explain.

When you call TDMS Open in LabVIEW, TDMS needs to load all the meta data information in tdms_index file, instead of just opening a file reference like txt or binary file does. So, as you mentioned, the more you deframent the file, the smaller the index file is, the quicker TDMS Open will be.