Question Backup process causing stuttering & freezing


Oct 30, 2018
I've been using the free Veeam client for local backup (to external HDD) for a while now, but recently I noticed the PC will occasionally stutter and even freeze for a moment while the scheduled backup is running. I've even had audio continue running while everything else froze up, though usually it will do the typical repeat stuttering thing or at least heavily crackle. It has not been doing this before, its a new thing. Also, it will always complete the backup, nothing actually crashes.

I've tried quite a few things already:
  • restarted (obviously)
  • checked if there had been an update to Veeam recently. In fact, it had never been updated (oops!), virtually excluding it being some kind of newly introduced bug
  • after updating to the latest version, the issue persists
  • checked drive health, all drives, internal SSD+HDD and external backup HDD, are healthy as far as CrystalDiskInfo goes
  • checked resource usage, CPU and other unrelated stuff is not highly taxed at any point, HDDs are all peaking around 100%
  • "throttle while system is busy" checkmark is and always has been checked in Veeam
I'm really running out of ideas here as to what it could be and how to diagnose it, any ideas?

Relevant hardware/software:
Win 7 whatever the latest update is with Veeam Agent as the backup software
i5 4590, 16GB RAM
internal Crucial BX100 250GB + some generic 1TB WD HDD, external Intenso enclosure showing up as a 3TB WD drive inside, connected via USB 3.0