Slow overnight running on nomachine session speeds up on interacting with the machine
This is an odd question, but it's had me scratching my head. I work on analysis of scientific data using MATLAB based packages, and I often login remotely using nomachine software to run code overnight, so the results are ready for me to inspect in the morning.
I've noticed a few times that when running code overnight, it seems to run extremely slowly. However, when I login in the morning to check progress, it immediately speeds up, simply through my interacting with the MATLAB window to check how it's doing.
It's a big speed change: a processing step that took 17 minutes during the night now takes 2. The speed-up was from the moment I logged on.
No-one else uses the machine, and nothing else, other than the gnome system monitor, is running on the machine. There is an automated night-time backup service, but there's no way that takes all night to run, although I'm wondering if it's somehow re-niceing my analysis code. However, on checking this morning the process has niceness 0, as usual. Also, no swap space is being used, and it's highly unlikely to be a RAM issue, as this analysis uses much less RAM than the machine has.
The machine is a 6-core workstation running SLED SUSE linux.
Any tips on what might be going on much appreciated!