How to Fix a Slow Computer Windows 10 — 10 Proven Fixes (2026)

Every program that launches at startup adds to your boot time and keeps consuming RAM in the background. Spotify, Teams, Discord, OneDrive, Skype, and dozens of other apps register themselves as startup items without telling you. Disabling the ones you don't need immediately is the fastest free fix available.

• Press Ctrl + Shift + Esc to open Task Manager, then click "More details" at the bottom if you see the compact view.
• Click the Startup tab. You will see every program that launches when Windows 10 boots, along with its "Startup impact" rating (High, Medium, or Low).
• Right-click any program you don't need immediately at login — such as Spotify, Discord, OneDrive, Teams, or gaming clients — and select Disable.
• Leave essential items enabled: your antivirus, audio drivers, and anything your IT department or employer requires.
• Restart your PC and measure the difference in boot time.

Windows 10 accumulates gigabytes of junk over time: temporary Internet files, Windows Update caches, old driver packages, Recycle Bin contents, and system error logs. Disk Cleanup is the built-in tool that safely removes all of it.

• Press Windows + R, type cleanmgr, and press Enter. Select your C: drive when prompted.
• Wait for the scan to complete, then check every box in the list — including Temporary Internet Files, Thumbnails, Recycle Bin, and Delivery Optimization Files.
• Click "Clean up system files" at the bottom left for a deeper scan. This often reveals an additional 2–8 GB from Windows Update leftovers.
• Click OK and then Delete Files to confirm. The process may take 5–15 minutes.
• To automate future cleanups, go to Settings → System → Storage and toggle Storage Sense to On. Configure it to run monthly and to automatically delete temporary files older than 30 days.

Malware — including cryptominers, adware, spyware, and trojans — is one of the most common causes of a suddenly slow Windows 10 PC. These programs run hidden processes that consume CPU and RAM continuously. Windows Security (formerly Windows Defender) is built-in, free, and highly capable.

• Click the Start menu, type Windows Security, and open the app.
• Click Virus & threat protection, then click "Scan options" below the Quick Scan button.
• Select Full scan and click Scan now. A full scan checks every file on your drive and takes 30–90 minutes depending on disk size.
• If threats are found, follow the prompts to quarantine or remove them, then restart your PC.
• As a secondary check, download and run Malwarebytes Free (malwarebytes.com) — it catches threats that Defender sometimes misses, particularly adware and PUPs (potentially unwanted programs).

Windows 10 enables dozens of visual animations and effects by default — window shadows, transparency, fade animations, and smooth font rendering. On older or lower-spec hardware, these effects consume meaningful CPU and GPU resources. Disabling them is instant and reversible.

• Press Windows + R, type sysdm.cpl, press Enter, then click the Advanced tab.
• Under the Performance section, click Settings.
• Select "Adjust for best performance" to disable all animations at once, or choose "Custom" and manually uncheck the most expensive effects (Animate windows, Fade menus, and Shadows).
• If you choose Custom, we recommend keeping "Smooth edges of screen fonts" checked — it has minimal performance cost but makes text much easier to read.
• Click Apply, then OK. Changes take effect immediately.

Outdated or corrupt device drivers — especially for graphics cards, chipsets, and storage controllers — can cause high CPU usage, stuttering, and 100% disk usage. Conversely, a recent driver update that introduced a bug may be the cause of a sudden slowdown, in which case rolling back is the fix.

• Right-click the Start button and select Device Manager. Look for any device with a yellow warning triangle — these indicate driver problems.
• To update: right-click the device and select Update driver → Search automatically. For graphics cards, always download the latest driver directly from Intel, AMD, or NVIDIA's website for the most up-to-date version.
• To roll back after a bad update: right-click the device, select Properties → Driver tab → Roll Back Driver (this button is grayed out if no previous driver is stored).
• Pay special attention to your storage controller driver (under IDE ATA/ATAPI controllers) — an incorrect driver here is a leading cause of 100% disk usage in Windows 10.
• Restart your PC after any driver change.

When Windows 10 runs out of physical RAM, it uses a portion of your hard drive as virtual memory (the pagefile). If the pagefile is too small, Windows constantly struggles to move data in and out, creating severe slowdowns. Manually setting a larger pagefile resolves this.

• Press Windows + R, type sysdm.cpl, press Enter, and go to the Advanced tab.
• Under Performance, click Settings → Advanced tab → Change (under Virtual memory).
• Uncheck "Automatically manage paging file size for all drives."
• Select your C: drive, choose Custom size, and set the Initial size to 1.5× your RAM in MB and Maximum size to 3× your RAM in MB. For example, with 8 GB RAM: Initial = 12288 MB, Maximum = 24576 MB.
• Click Set, then OK, and restart your computer for the change to take effect.

On traditional spinning hard drives, files become fragmented over time — split into pieces scattered across the disk platters. The read head has to physically travel farther to assemble each file, which slows read speeds significantly. Windows 10 should auto-defrag weekly, but it's worth verifying.

• Type Defragment in the Start menu and open "Defragment and Optimize Drives."
• Select your C: drive and check the Media type column. If it says Hard disk drive, click Optimize to defragment. If it says Solid state drive, Windows runs TRIM instead — also click Optimize to send the TRIM command manually.
• Under Scheduled optimization, confirm it is set to Weekly so your drive stays optimized automatically.
• Never manually defragment an SSD — it provides no benefit and unnecessarily wears the drive. Windows handles this correctly on its own via TRIM.
• Allow the optimization to complete — defragmenting a heavily fragmented 1 TB HDD can take 1–3 hours.

Many programs — especially free software, toolbars, manufacturer bloatware on new PCs, and old utilities — install background services and scheduled tasks that run even when you never open the app. Uninstalling them removes the clutter and frees disk space.

• Go to Settings → Apps → Apps & features and sort the list by Size to identify the largest programs first.
• Scroll through the full list and uninstall anything you don't recognize or haven't used in the past six months. Be thorough — old games, trial software, and manufacturer utilities are common culprits.
• Pay special attention to toolbars, download managers, and "optimizer" software — these are frequently adware in disguise and slow Windows significantly.
• After uninstalling, check Task Manager → Startup tab again, as some programs leave startup entries behind even after uninstall.
• Restart your PC after removing multiple programs.

The Windows registry accumulates orphaned entries from uninstalled programs over time. While Microsoft itself downplays the direct performance benefit of registry cleaning, removing thousands of broken entries can resolve specific application errors and occasional startup slowdowns. CCleaner Free remains the most trusted tool for this task.

• Download CCleaner Free from ccleaner.com — choose the free version, and uncheck any bundled offers during installation.
• Before running the registry cleaner, go to File → Export Registry in CCleaner to create a backup you can restore if anything goes wrong.
• Click Registry in the left menu, then Scan for Issues. Review the list of found issues.
• Click Fix Selected Issues and save the backup when prompted. Allow CCleaner to fix all found issues.
• Use CCleaner's Custom Clean tab to also clear browser caches, Windows temp files, and recent document history for a more thorough cleanup.

If your PC is still running a traditional spinning hard drive and all the software fixes above haven't solved the slowness, a hardware upgrade is the answer. Replacing the HDD with a SATA SSD is the single most impactful upgrade you can make to an older Windows 10 computer — and it's often more cost-effective than buying a new machine.

• Confirm you have an HDD: open Task Manager, click the Performance tab, then click Disk 0. If it says "Hard disk" under the graph, you have an HDD. SSDs will say "SSD."
• Purchase a compatible SATA SSD sized to match or exceed your current drive (a 500 GB Samsung 870 EVO or Crucial MX500 are excellent value options in 2026 at approximately $60–80 CAD).
• Use free cloning software like Macrium Reflect Free or Samsung Data Migration to clone your existing Windows installation to the new SSD — no reinstall needed.
• Physically swap the drives (requires opening the laptop or desktop — follow a model-specific guide on iFixit.com if unsure).
• Boot from the SSD, confirm Windows loads correctly, then enable TRIM: open an elevated Command Prompt and type fsutil behavior query DisableDeleteNotify. A result of 0 means TRIM is already active.