How to troubleshoot disk performance issues

[Qubes]

I recently got my hands on a Dell XPS 15 9560. I have been using it for
about a month now, and although general performance hasn’t been on par,
for reasons still unclear to me, at least compared to my old Dell
Latitude E6520 which has significantly less resources, yesterday things
really just came to a crawl.

Since the machine is roughly 10 years old, i suspect memory or the SSD
could be the cause, but i do not know how to test this on Qubes.

Can someone please recommend a way for me to test these two components?

Everything is dog slow, even just scrolling on a page, if i drag the
slider or scroll the mouse wheel, there is quite a delay in it actually
happening, to the point where the machine is generally just not useable.
Spinning up a DVM has gone from 15 seconds to 65 seconds. Which of
course tends to let me think the SSD is failing, but i would like to try
and have some degree of certainty before i spend money on a new SSD,
only to install it and still have the same performance issues.

I do plan on upgrading both memory, from the current 32 to 64 GB, and
the SSD, just a better SSD than the Toshiba the machine shipped with,
but if my underlying issues are neither of the two it will all be in vain.

[Ulrich Windl]

Hi!

Just a rough guess: If the CPU cooling system (e.g. fan) is defective the CPU may run at minimal speed (thermal throttling).
To rest the RAM I'd suggest to run memtest86 as standalone boot.
For the SSD you could run a short or long self test using smartmontools (smartctl), or just inspect the performance attributes.

Regards,
Ulrich