Why is Debian slow?

Question

linux

Hello, I need help with Debian.
This OS started to slow down a bit. Loading is normal, there are no errors, but when it comes to Xs, hangs begin. Applications (graphic) are loaded a little longer than before, sometimes urxvt slows down if you operate from root.
Before it all started, I rebooted a couple of times with SysRq (REISUB). The first time due to the fact that I accidentally unmounted the root, and the second time the computer just hung. Yes, I recently installed Banshee, after it it started to slow down even more, then I demolished it.
In what there can be a reason of such strange brakes.
Debian Jessie system, kernel 3.11.
And yes, in general, how can you see the contamination in Debian.
Thank you in advance.

Answer 1

fsck all partitions, maybe your fs needs to be fixed.
and at the same time the presence of a checksum of all files, maybe something was broken in the process of reboots.

Answer 2

Have you lost your video drivers? (glxinfo glxgears to help you)

Answer 3

Is the problem with the driver relevant if I have an Intel HD?