A new PC game often stutters badly during its first hour and runs smoothly afterwards. The cause is shader compilation, and it is a consequence of how PC hardware differs from a console.
Shaders must be compiled for the exact hardware
A shader is a small program that runs on the graphics processor to determine how surfaces are drawn. It is written once but must be translated into instructions for a specific chip and driver version.
A console has one hardware configuration, so this translation is done during development and shipped with the game. Nothing is compiled on the player's machine.
A PC has thousands of combinations of graphics chip, driver and operating system build. The developer cannot precompile for all of them, so the work is deferred to the player's computer.
Compiling during play causes the hitch
If a shader is compiled the first time it is needed, the frame that needs it waits. That wait appears as a freeze lasting a fraction of a second.
The freezes cluster around new visual events: a weapon fired for the first time, an unfamiliar enemy, a new area. Each introduces shaders that have not been seen.
Once compiled, results are cached on disk, so the same moment runs smoothly later. This is why the problem fades and then returns after a driver update clears the cache.
Precompilation moves the cost to a loading screen
Games can compile shaders at startup instead, which is the loading step some titles run on first launch or after driver changes. The stutter is converted into a wait.
The wait can be long on modest processors, because compilation uses the central processor rather than the graphics card. More cores make it faster.
Players often dislike the delay, but it is the same work either way. The choice is whether to pay it once up front or repeatedly during play.
Engine architecture makes it harder for some games
Games that generate visual combinations dynamically have far more possible shaders than a designer can enumerate in advance. Precompiling everything is not practical.
Such games can instead compile in the background while the player is in a menu or an early area, accepting some misses. This reduces but does not remove the hitching.
The severity of the problem therefore tracks how a game's rendering is built, which is why two titles on the same engine can behave very differently.
Why faster hardware does not solve it
Compilation is bounded by processor throughput and by when the shader is first requested, not by graphics performance. A powerful graphics card sits idle during the pause.
Faster storage helps only with reading the cache, which is not the slow part. The bottleneck is generating the code, not loading it.
This is why the complaint appears on high-end machines as loudly as on modest ones. The stutter is a scheduling problem, and hardware cannot reschedule it.