If the computer is used for a long time without proper maintenance, its performance will deteriorate. If the performance of your computer has noticeably dropped or you need to get your old computer working properly, take certain steps. To fix errors or troubleshoot problems, simply restart your computer. If the system is infected with malicious codes, scan it with appropriate programs.
Steps
Part 1 of 6: Basic Steps

Step 1. Restart your computer if you have problems
Remember that restarting your computer can fix more problems than you think. Be sure to save your open documents before rebooting.

Step 2. Restore the network if you cannot connect to the Internet
To do this, restart your network equipment. This can often solve the problem with the connection to the modem and router.
- disconnect the power cable from the modem and the router (if there is one);
- wait about thirty seconds, and then connect the power cable to the modem;
- when the modem lights turn on, connect the power cable to the router; try connecting to the network in a minute.

Step 3. Check the clock on the computer
If the system clock is showing the wrong time, the system will not download security certificates from websites. This can lead to problems loading many web pages. Check the system clock and set the correct time.

Step 4. Restart the printer if you cannot connect to it
Do this if your printer does not appear in the Print window. Turn off the printer using the power button, or unplug the power cord from the printer. Wait about thirty seconds and then plug in the cable or press the button.
Part 2 of 6: How to Remove Malware and Clean Browsers (Windows)

Step 1. Open Control Panel
If web browsers are slow, lots of pop-ups open, unknown toolbars are present, the system is most likely infected with malware. Such a program attacks the browser, which leads to redirects to unknown pages and the appearance of numerous pop-up windows. To get rid of the malicious code, first uninstall unknown programs through the Control Panel. This process depends on the Windows version:
- in Windows 8/10, right-click on the Windows button and select "Control Panel" from the menu;
- in Windows XP / Vista / 7, click the "Start" button and select "Control Panel".

Step 2. Select "Uninstall a program" or "Programs and Features"
A list of all programs installed on your computer will open.

Step 3. Find recently installed programs that you do not know
You can sort the list by installation date to find programs that were recently installed and possibly without your knowledge. Go through each program on the list and take a look at the ones you don't know. Search the Internet for information about each unknown program to find out if it is malicious.

Step 4. Select the malware and click Remove
Follow the instructions on the screen to uninstall the program. Repeat this with other unwanted programs.
You can also uninstall programs that you know but don't use. For example, old games, unused browsers and utilities, and other programs that are not malicious can slow down your computer. Uninstall these programs to free up space and speed up computer startup

Step 5. Install AdwCleaner
It is a free program that finds and removes malware. It can be downloaded from toolslib.net/downloads/viewdownload/1-adwcleaner/.

Step 6. Open AdwCleaner
Click “Scan” to start scanning your computer for infections. This process can take about 20 minutes. When the scan is complete, click "Clean" to remove any infected files found.

Step 7. Install Malwarebytes Anti-Malware
The free version of this program can find and remove most infections. The program can be downloaded from malwarebytes.org by clicking Free Download. Double click on the downloaded installation file to install the program.

Step 8. Open Anti-Malware
Update this software if prompted. Run a computer scan, which will take 20-30 minutes. When the scan finishes, delete all detected files - to do this, click "Quarantine".

Step 9. Download and run the utility for cleaning shortcuts
Many malware add links to browser shortcuts to redirect you to other sites. Keep in mind that such links will not disappear if the malware itself is removed. Therefore, use a free utility that will check all shortcuts and remove malicious links. The utility can be downloaded here. Run the downloaded utility to quickly check and fix browser shortcuts.

Step 10. Reset browser settings
Elements associated with the removed malware may remain in web browsers. Therefore, reset your browser settings to factory defaults:
- in Internet Explorer, click Tools> Internet Options. Go to the Advanced tab and click Reset. Check the box next to "Delete personal settings" and click "Reset";
- in Chrome, tap Menu> Settings> Advanced. Scroll down the page and tap Restore Settings> Reset Settings;
- in Firefox, click Menu>? Select Troubleshooting Information and double-click Refresh Firefox.

Step 11. Restart your computer and run Anti-Malware and AdwCleaner again
When you remove the malware, restore the shortcuts and reset browser settings, restart your computer and run the scan of the computer with the specified programs again. There may still be files associated with the removed malware on the system.
Part 3 of 6: How to Remove Malware and Clean Browsers (Mac OS X)

Step 1. Remove unknown programs from the Applications folder
This folder contains all programs installed on the computer. If it contains suspicious programs that you do not know, drag them to the trash can to remove it.
Search the Internet for information about each unknown program to find out if it is malicious

Step 2. Install Malwarebytes Anti-Malware for Mac computers
It is called AdwareMedic and is one of the most effective tools for finding and removing malware on Mac OS X. Download it for free from malwarebytes.org/antimalware/mac/.
- When the installer downloads, double-click it and drag the Anti-Malware for Mac icon to the Applications folder.
- If you see a message stating that the program cannot be installed because it was not downloaded from the App Store, right-click the downloaded file (or hold Ctrl and left-click) and then click Open> Open.

Step 3. Open Anti-Malware for Mac and run a computer scan
When you start the program for the first time, you will be prompted to enter the administrator password. This is necessary to remove files from protected areas that require special privileges. Click Scan to run a malware scan on your computer. This process will take about 15–20 minutes.

Step 4. Click on "Remove Selected Items" when the scan is complete
All files found that pose a threat will be deleted. You may need to restart your computer to complete the process.
Part 4 of 6: How to Optimize Your Computer (Windows)

Step 1. Update Windows
Installing available updates fixes errors, keeps your computer stable, and increases its security. You can check for updates and download them using the Update Center. Open the start menu and type updates to find Windows Update.
In Windows 10, open the Settings menu and then click Update & Security> Update Center

Step 2. Check the free space of the system disk
As a rule, it does not significantly affect the performance of the computer, but if the free volume of the system disk drops below 20%, the system will slow down a little. Windows uses free space to move and store temporary files, so without free space, system performance will slow down. To maintain system performance at the proper level, regularly delete old and unnecessary files.
Open the Computer window. Press ⊞ Win + E and find your system drive (usually the C:) drive. For maximum performance, the free space on this drive must be at least 20% of the total drive capacity

Step 3. Run the Disk Cleanup utility to find and delete old temporary files
Open the start menu and type "disk cleanup" to find this utility. Select the system drive and wait for the utility to scan it. Check the boxes for each file type you want to delete. Next to the file types, you will see the size that will be freed after the files are deleted.
Look for junk or old files in the Downloads and Documents folders

Step 4. Remove old and unused programs
As you work on your computer, many programs are installed on it, and some of them you do not use. Such programs take up disk space, and some of them run in the background and consume system resources. Therefore, regularly remove unused programs to keep your computer running smoothly.
- Open Control Panel and select "Uninstall a Program" or "Programs and Features". Review the list of installed programs and remove those you no longer use. Highlight the program and click Uninstall to uninstall it. If you do not know the program, look for information about it on the Internet.
- The free PC Decrapifier scans your computer for unnecessary programs. Such programs are sometimes referred to as bloated software. PC Decrapifier can be downloaded for free at pcdecrapifier.com. This program does not need to be installed - just run it to scan your computer. If PC Decrapifier finds a bloated program, it will be removed.

Step 5. Remove programs from startup
Many programs start when Windows boots. This way, some necessary programs start faster, but an excessive number of programs at startup can greatly slow down the boot of the Windows system:
- on Windows 8/10, press Ctrl + ⇧ Shift + Esc to open the Task Manager. Click Details to expand Task Manager and then click the Startup tab. Select the programs you want to remove from startup and click Disable. If you do not know what this or that program is intended for, look for information about it on the Internet;
- in Windows Vista / 7 press ⊞ Win + R and type msconfig. Go to the Startup tab. Uncheck the box next to each program that you want to remove from startup. If you do not know what this or that program is intended for, look for information about it on the Internet - just enter the name of the program in a search engine and view the first search results.

Step 6. Use analogs of some programs
Many popular programs are poorly optimized and slow down your computer. These programs include Norton Antivirus, iTunes, and Adobe Reader. These programs have free counterparts, the use of which speeds up the computer.
- Use the preinstalled Windows Defender Antivirus instead of Norton. You can also install the free Avast or Bit-Defender antivirus. Read this article to learn how to use Windows Defender.
- Instead of iTunes, you can use the media player foobar2000 or MediaMonkey (both programs support syncing with an iOS device).
Part 5 of 6: How to Optimize Your Computer (Mac OS X)

Step 1. Install available updates
Mac OS X and software updates help keep your system running smoothly. By default, updates are installed automatically, but you need to check them manually from time to time to ensure that important updates are not missed.
Open the Mac App Store and go to the Updates tab at the top of the window. Review and install all available system and software updates

Step 2. Check the free space of the system disk
If the free space is low, the performance of the computer will degrade. In this case, delete old and unnecessary files and programs to improve the speed of your computer.
- To remove old programs, drag them from the Applications folder to the Trash.
- Look for junk or old files in the Downloads and Documents folders.
- CleanMyMac3, Disk Inventory X, and DaisyDisk help you find and delete unneeded files. With these programs, you can free up a significant amount of the system disk.
- Use the Monolingual program to remove unused language files. This program can be downloaded for free at monolingual.sourceforge.net/. Do not delete the required languages (including Russian and English), as this may lead to problems with the operating system.

Step 3. Remove unnecessary icons from the desktop
If the desktop is full of icons, it can slow down the system. Remove shortcuts and files from the desktop to improve system performance.

Step 4. Remove programs from startup
Many programs start when Mac OS X boots up. This way some programs that you need start up faster, but too many startup programs can slow down the system boot significantly.
- open the Apple menu and select "System Preferences";
- click Users and Groups> Login Items;
- select the program you want to remove from startup and press "-". You may need to click on the padlock icon and enter your administrator password first.

Step 5. Check the hard drive with Disk Utility
Sometimes files and permissions get corrupted, which can cause system problems. The preinstalled Disk Utility will scan the disk and fix any problems it finds.
- open the Applications> Utilities folder and click Disk Utility;
- select the system drive in the left pane;
- go to the First Aid tab and click Check Disk. The disk scan will start, which may take some time;
- click "Repair Disk" if the scan found errors.
Part 6 of 6: How to keep your computer stable

Step 1. Be careful when downloading software from the Internet
Remember that during the installation of the program you need, additional programs that contain malicious code may be installed. If you launched the installation of a program that you downloaded from the Internet, read the information in each installer window (especially if it is a free program). Refuse to install additional programs and always check which options are checked.
- Look for open source alternatives that typically do not contain malicious code.
- Do not download programs from CNet and Tucows services, as they contain unwanted software.

Step 2. Run Fast Antivirus
If you are using a Windows computer, install an antivirus that will work on a permanent basis. You can turn on Windows Defender, but it's better to install a third-party antivirus like Comodo, Avast, or Bit-Defender. Remember: only one antivirus must be installed on your computer to avoid conflicts.
For information on how to find and install antivirus software, see this article

Step 3. Wipe off dust regularly
Excessive dust can cause computer components to overheat - in which case they will reduce their performance to cool down. Therefore, keep your computer clean and cool so that it always performs at its best. This is especially true if you have pets or smoke.
- Use cans of compressed air or an air compressor to remove dust from the computer case.
- This article provides tips on how to clean your computer.

Step 4. Remove programs if you do not need them
If only those programs that you regularly use are installed on your computer, it will work stably for a long time. Uninstall unnecessary programs to free up space. If you want, do not delete the installation files of the programs in order to quickly install them if necessary.