What the Prefetch folder actually contains
Every time you start a program, Windows writes a small .pf file into C:\Windows\Prefetch — typically between 4 and 40 KB. The file records which parts of the program's executable and its libraries were loaded, in which order, and from which disk locations. On the next launch, Windows uses this trace to read the files in the optimal order, which shortens loading times noticeably on hard drives and a little on SSDs.
The folder is self-managing. Alongside the .pf files sits a Layout.ini that describes the ideal file layout for defragmentation, and the ReadyBoot subfolder stores boot traces. The number of prefetch files is capped too: after roughly a thousand entries Windows automatically drops traces of programs you no longer use, so the folder stays at a few MB even after years.
- .pf files — one launch trace per application, typically 4–40 KB each
- Layout.ini — the ideal file-layout plan compiled from all those traces
- ReadyBoot subfolder — traces used to speed up the boot sequence
- Typical total size — a few MB; anything beyond 20–30 MB is unusual
- Self-cleanup — at about a thousand files, Windows drops unused traces on its own
The myth: deleting Prefetch files makes Windows faster
Countless “optimizer” guides recommend emptying C:\Windows\Prefetch, and the myth survives because the folder gets labeled a “cache”. In reality the opposite is true: after a wipe, Windows has no launch traces left, so every program starts the slow, unoptimized way again. First launches after cleaning are measurably slower, and the traces need several runs of each app to rebuild fully.
The folder also cannot bloat: it is capped and self-cleaning, so there are no gigabytes to free. The only real scenarios for deleting .pf files are a corrupted trace that makes one specific app hang on launch, or the wish to erase the launch history. Even then Windows starts recording again immediately. For speed, leave Prefetch alone.
If you still want to clean it — and where the real junk is
If you have a specific reason, the procedure is simple: open C:\Windows\Prefetch with administrator rights, select the .pf files and delete them. A command like del C:\Windows\Prefetch\*.pf /q does the same in one line. Files currently in use are skipped, and every trace is recreated within a few launches. Expect the next round of app starts to be a touch slower — that is the whole cost and the whole effect.
The honest performance win lives elsewhere: temp files, update leftovers, Delivery Optimization caches and browser caches regularly amount to gigabytes, unlike Prefetch's handful of megabytes. This is why serious cleaners leave the Prefetch folder alone by design. Kleaner PRO's junk scanner, for example, deliberately skips C:\Windows\Prefetch and targets the folders where space is actually lost — so a cleanup pass frees real disk space instead of a placebo.
Questions and Answers
Is it safe to delete files in the Prefetch folder?
Yes, it is safe — Windows rebuilds every .pf file automatically. But it does not make your PC faster; the next launches are slightly slower until the traces are recreated.
Why is my Prefetch folder empty?
Most often prefetching is disabled — via the EnablePrefetcher registry value or some “optimization” tool. The folder is also nearly empty right after a cleanup or on a fresh Windows install where few apps have run.
How big should the Prefetch folder be?
A few megabytes — the internal cap and self-cleanup keep it from growing. If you see gigabytes, you are looking at the wrong folder, and Prefetch still is not the problem.
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