Unstable processing speed of SNAP

Hello everyone,

I noticed that there some discussion about the processing speed of SNAP. Yet, my problem is a slightly different one.

I found that the processing of SNAP is “very fast” once in a while. Take the enhanced spectral diversity or subset for example. For my datasets, usually it will take about 1 hour for one stack. However, occasionally, I will encounter one or two runs, in which it will be quite fast, taking less than 10 minutes! But soon it will go back to “normal speed” (~ 1 hour) again.

So, my question is, which speed should be the expected normal speed? The slower but often met 1 hour? Or the faster but rarely met 10 minutes?
And, are there any settings or operations of SNAP that I can take to speed up the processing?

I did all the processing on a Win 7 64bit PC, with totally 64GB RAM and a i7-7700 3.60 GHz CPU.