Linux Runs Slow After an Update: How to Fix It
How to diagnose whether it's the kernel, a graphics driver, or a new background service.
1. A new kernel with mismatched graphics drivers
This is the most common cause. Check which kernels you have installed:
uname -r
If you use proprietary NVIDIA graphics, confirm the module was correctly recompiled for the new kernel — reinstalling the driver usually fixes it.
2. Too many old kernels piled up
They don't slow down the running system, but they do take up space and lengthen the boot menu. You can clean them up:
sudo apt autoremove
3. A new service turned on by the update
systemctl list-units --type=service --state=running
Compare with what you remember from before — a new service consuming resources in the background is a real cause, though less common.
Tip: if the previous kernel is still available in the boot menu (GRUB), booting into it temporarily confirms whether the problem is specific to the new kernel or something else.
Frequently asked questions
Why specifically after updating the kernel?
Proprietary drivers (like NVIDIA's) sometimes don't recompile correctly for the new kernel automatically, causing worse graphics performance until you reinstall them.
Should I remove old kernels?
It's safe to do with 'apt autoremove', though it's worth keeping at least one previous one as a backup in case the new one gives problems.