Slowing on XPsp3 when Avast using windows programs to write to SSD

Hello,
Been having noticeably slow writes to SSD, I can look in task manager and see Avast along with a few other .exe’s writing to the SSD. I’m assuming Avast is generating the write to the SSD but for some reason it slows everything down to nearly a stop. Lsass.exe seems to be the bottleneck as I can watch I/O write bytes racking up (along with Avast) and a few other exe programs are writing to the SSD at the same time. It can take up to a minute to do its thing (HDD light remains lit) then its back to normal. When I drop the internet and disable Avast, things are back up to speed.

No other system problems except for this one, seems to be happening more frequently, once 10-20 minutes or so.
Would be nice if I can see what else Avast is doing to narrow this down. Browser in use is Firefox, 4G RAM. Turned off browser cache to speed it up and keep from consuming the SSD.
Thanks for any help,
Bryan