The video driver causes short freezes from time to time, especially if
an external monitor is attached. Adding the i915.enable_psr=0 kernel
parameter mitigates those freezes.
This is a known problem for the X260, as mentioned in the Arch Wiki. It
occurred mainly after switching to kernel version five.
With switching from NixOS 20.03 to 20.09, the services.tlp.extraConfig
option became deprecated and was replaced by services.tlp.settings.
The ThinkPad X260 is only device within nixos-hardware which makes use
of this configuration.
