Is Your SSD Slowing Down? Discover the Hidden Windows Fix

Published Apr 25, 2026, 6:00 AM EDT

Tashreef's fascination with consumer technology began in the school library when he stumbled upon a tech magazine, CHIP, which ultimately inspired him to pursue a degree in Computer Science. Since 2012, Tashreef has professionally authored over a thousand how-to articles, contributing to Windows Report and How-To Geek. He currently focuses on Microsoft Windows content at MakeUseOf, which he has been using since 2007.

With hands-on experience building websites and technology blogs, he brings practical developer insights to his technical writing. You can view his complete work portfolio at itashreef.com.

You might also stumble upon his short how-to video explainers, simplifying complex topics. Beyond writing, Tashreef enjoys creating short explainer videos, gaming, and exploring animated shows.

Sign in to your MakeUseOf account

It's hard to associate slowness with an SSD. But over time, your new SSD will slow down, causing longer boot times, poor file transfer speeds, and weak benchmark results. It's tempting to write this off as the drive wearing out or the usual cost of running Windows for a few years.

While those do play a part, there's another reason your SSD is slowing down, and it has nothing to do with age. Windows ships with a maintenance job that's supposed to run on its own and optimize your SSD for the best performance, and on a healthy system, it works. However, it can silently stop running after an update or driver change, and nothing in Windows will tell you it's been broken, causing degraded SSD performance.

Quiz

8 Questions · Test Your Knowledge

Windows Storage Through the Ages
Experts Only!

From floppy disks to bloated SSDs — do you really know the history and quirks of Windows storage?

Drive LettersSSD & HDDWindows FeaturesStorage HistoryNiche Storage

Begin

Why do most Windows systems start their primary hard drive at the letter C: rather than A: or B:?

AC stands for 'Core drive,' a term used by early IBM engineersBA: and B: were reserved for floppy disk drives in early PCsCMicrosoft skipped A: and B: to avoid conflicts with DOS network drivesDThe letters A and B were used by CD-ROM drives in the original IBM PC

Correct! In early IBM PCs, A: and B: were assigned to the two floppy disk drives that most machines shipped with. When hard drives arrived, C: was simply the next available letter — and the convention stuck even as floppies became obsolete.

Not quite. The answer is B — A: and B: were reserved for floppy disk drives. Early PCs often had two floppy drives before hard drives were common, so when hard drives arrived they naturally inherited the next available letter, C:.

Continue

Which Windows 11 feature is most notorious for quietly consuming gigabytes of SSD space through stored system snapshots and restore data?

AWindows Search IndexingBHibernate File (hiberfil.sys)CSystem Protection and Restore PointsDWindows Subsystem for Linux

Correct! System Protection creates restore points that can collectively consume many gigabytes over time. Each snapshot captures system file states, and Windows keeps multiple versions — silently eating into your SSD space until you review or disable the feature.

Not quite. The biggest hidden space hog from snapshots is System Protection and Restore Points. While hiberfil.sys is also large, restore points accumulate over time and can quietly consume a significant chunk of your drive without obvious warning.

Continue

What was the approximate storage capacity of the floppy disk used in the original IBM PC released in 1981?

A1.44 MBB720 KBC160 KBD360 KB

Correct! The original IBM PC used single-sided, double-density 5.25-inch floppy disks with a capacity of just 160 KB. To put that in perspective, a single modern smartphone photo is hundreds of times larger than an entire floppy disk from 1981.

Not quite. The original 1981 IBM PC used 160 KB single-sided floppy disks. The more familiar 1.44 MB floppy didn't arrive until the late 1980s, and 360 KB double-sided disks came slightly after the original model.

Continue

What does the acronym NVMe stand for in the context of modern SSD storage?

ANon-Volatile Memory ExpressBNetwork Volume Management EngineCNext-gen Virtual Memory ExtensionDNon-Volatile Multi-channel Exchange

Correct! NVMe stands for Non-Volatile Memory Express. It's a communication protocol designed specifically for solid-state drives that connects directly over PCIe, drastically reducing latency compared to the older SATA interface that was originally designed for spinning hard drives.

Not quite. NVMe stands for Non-Volatile Memory Express. It replaced the older AHCI protocol and was purpose-built for flash storage, allowing SSDs to fully unleash their speed potential by communicating directly over the PCIe bus.

Continue

The Iomega Zip drive, popular in the late 1990s, had an infamous failure mode that earned what colorful nickname?

AThe Blue Screen of DrivesBThe Click of DeathCThe Spin Crash SyndromeDThe Zipper Fault

Correct! The 'Click of Death' was a well-documented Zip drive failure where a mechanical fault caused a distinctive repetitive clicking sound — and often destroyed not just the disk inside but also corrupted other disks inserted afterward. It became one of the most feared storage failure sounds of the era.

Not quite. The dreaded failure mode was called the 'Click of Death.' The distinctive clicking sound signaled a head alignment failure, and the damaged drive could even corrupt other Zip disks inserted into it — spreading the damage like a hardware virus.

Continue

Which hidden Windows system file stores the contents of RAM to enable the hibernate function, and can often be several gigabytes in size?

Apagefile.sysBswapfile.sysChiberfil.sysDwinmem.sys

Correct! hiberfil.sys is the hibernate file, and its size corresponds directly to the amount of RAM in your system — if you have 16 GB of RAM, it can be up to 16 GB. Disabling hibernation via the command 'powercfg /h off' removes it entirely and can instantly reclaim significant SSD space.

Not quite. The hibernate file is hiberfil.sys. It's separate from pagefile.sys (the virtual memory paging file) and swapfile.sys (used by modern apps). Hiberfil.sys saves your entire RAM state to disk so Windows can restore your session after a full power-off.

Continue

Which storage technology, common in enterprise and niche consumer markets in the 2000s, used a spinning magnetic disk inside a removable cartridge and was often called a 'super floppy'?

AJAZ DriveBLS-120 SuperDiskCSyQuest EZDriveDCastlewood Orb

Correct! The LS-120 SuperDisk held 120 MB on a high-density magnetic disk and was backward compatible with standard 1.44 MB floppies. It was briefly considered a potential floppy replacement and appeared in some PC models of the late 1990s, though it ultimately lost out to CD-RW and USB drives.

Not quite. The LS-120 SuperDisk earned the 'super floppy' nickname. While the Iomega JAZ and SyQuest drives were also removable magnetic cartridge drives of the era, the LS-120 was specifically marketed as a direct floppy successor due to its physical similarity and backward compatibility.

Continue

In Windows, what is the maximum number of drive letters available for assignment to drives and partitions?

A24B26C23D28

Correct! While the English alphabet has 26 letters, A: and B: are traditionally reserved for floppy drives, leaving 24 usable drive letters from C: to Z:. This limitation, inherited from DOS, can become a real headache for servers or enthusiast builds with many drives, partitions, and network shares.

Not quite. The answer is 24. Although there are 26 letters in the alphabet, A: and B: are conventionally reserved for legacy floppy drives, leaving C: through Z: — exactly 24 letters — for hard drives, SSDs, optical drives, USB sticks, and network shares.

See My Score

Challenge Complete

Your Score

/ 8

Thanks for playing!

Try Again

SSDs slow down as they fill up

The cache shrinks when free space runs out

Most consumer SSDs use TLC flash, which stores three bits per cell. But TLC is slow to write to directly, so the controller sets aside a chunk of empty cells and writes to them as if they were SLC (one bit per cell). This SLC cache is what lets your drive hit its advertised peak speeds during short bursts. If you're curious about the finer details, here's a good primer on how solid-state drives actually work under the hood.

The catch is that the cache is carved out of free space. When your drive is nearly full, there are fewer empty cells available to act as cache. Large writes quickly overflow what little cache remains and fall back to direct TLC speeds, which can be a fraction of the peak. On some drives, sustained write speed drops from several gigabytes per second to well under half of that once the cache runs out.

Related

Free space also matters for the controller's background housekeeping. Blocks must be erased before they can be rewritten, and that erase cycle needs room to maneuver. With almost every block in use, the controller struggles to keep a pool of pre-erased blocks ready, which adds latency to every subsequent write.

Partitioning won't save you here. The controller manages flash layout internally, so making an extra partition or leaving one unmounted doesn't physically reserve any cache area. Keeping a healthy chunk of free space on the drive is the only thing that reliably helps.

WinSAT tells you how fast your SSD actually is

A built-in benchmark to check your storage drive speed

A good way to tell if your SSD is not working at its best is to run a benchmark test to see if you are still getting the speed it's rated for. There are many ways to test your SSD speed and performance, but for a quick check, you can use another lesser-known but handy built-in tool called WinSAT.

WinSAT is the command-line engine behind the old Windows Experience Index. Microsoft removed the user-facing score screen years ago, but the tool itself still ships with Windows 10 and 11. To use it, press Win, type cmd, and choose Run as administrator. Then run winsat disk -drive C (replacing C with your SSD's drive letter).

The test finishes in a few minutes and prints sequential read, sequential write, and random I/O numbers directly in the console. You can compare these against your drive's rated speeds on the manufacturer's spec sheet. If the sequential write number is sitting well below what the drive was sold at, that's your first real hint that something is off.

I like WinSAT because it's fast, doesn't need an install, and gives me a number I can act on. It's not as detailed as CrystalDiskMark, but for a quick sanity check before I start troubleshooting, it's exactly what I need.

TRIM keeps your SSD fast, and Windows already has it

The maintenance job that quietly goes missing

Traditional hard drives get defragmented. The idea is to shuffle file pieces back next to each other so the read head doesn't have to jump around. SSDs have no moving parts, so defragmenting them doesn't help, and the extra writes just wear out the flash. What SSDs need instead is TRIM.

TRIM is a command that tells the SSD controller which blocks no longer hold valid data, so it can pre-erase them and keep a pool of clean blocks ready for new writes. Without TRIM, the drive has to do a slower read-erase-rewrite cycle every time it writes to a used block, and write speeds tank. Windows is supposed to send TRIM commands automatically on a schedule, but that schedule can quietly stop working after a system update or a driver change, and the drive gives you no warning.

To run TRIM manually, open an elevated terminal and type defrag /O C: (again, replace C with your SSD's letter). The /O switch tells Windows to use the right optimization for the drive type, which means TRIM on an SSD, not a classic defrag. The run can take a few minutes. On a neglected SATA SSD, you can sometimes see a 20-30% write speed recovery afterwards. On a healthy NVMe drive, the change is usually small, which is actually good news: it means background TRIM has been working all along.

To make sure it keeps working, search for Defragment and Optimize Drives in the Start menu and open the tool. Find your SSD in the list and check the Scheduled optimization column. It should say On. If it doesn't, click Change settings and turn it on. Windows then runs TRIM weekly, which is enough for almost everyone.

Windows 11 is Microsoft's latest operating system featuring a centered Start menu, Snap Layouts, virtual desktops, enhanced security with TPM 2.0, and deeper integration with Microsoft Teams and AI-powered Copilot.

Keep your expensive purchase feeling fast!

After running defrag /O on my main drive, I saw my sequential write speed climb back to where it should be, and the schedule had silently been off for months. That's the part that bothers me most: there's no notification, no warning banner, nothing. The drive just gets slower, and you blame the hardware.

If your SSD feels sluggish, run WinSAT first, then defrag /O, and check the schedule. It takes ten minutes, costs nothing, and often solves the problem without you having to buy a new drive or reinstall Windows. The fix has been built in the whole time. Windows just forgot to tell you about it.