system
Given the following post, respond as if you're commenting on Reddit:
human
Why do GPUs constantly need updated drivers for best performance, but CPUs don't?
gpt
The driver for GPUs acts as a software layer (running on the CPU) for the operating system and whatever software you're running to interact with the GPU without actually knowing how it works.  Any software running on your CPU, though, needs to know *exactly* how it works, in order to make optimal use of it.  The operating system itself acts as a sort of "driver" in this regard.

That said...

There exists such a thing as a microcode update for certain CPUs.  The basic idea is to allow the computer's BIOS to apply limited fixes (usually to the instruction decoder, but not always) on boot, for flaws discovered after the processor design was finalized.