How to Reduce RAM Usage and CPU Load in Linux

The Linux operating system has long established itself as a reliable, flexible, and high-performance environment suitable for servers, workstations, and embedded systems alike. However, even such a stable system can slow down under heavy resource load. If your RAM is maxed out and the CPU is constantly running at full capacity, it not only impacts usability but can also lead to lags, freezes, and even crashes.

This becomes especially critical when using Linux in professional environments—such as data centers, corporate servers, or development setups. That's why it’s important to regularly optimize the system and monitor resource usage to maintain responsiveness and stability.

In this detailed guide, we’ll go over practical ways to reduce CPU and RAM load. We’ll talk about process monitoring, managing startup applications, kernel tweaks, lightweight software alternatives, and other tips suitable for both beginners and experienced users.

Identify Resource-Intensive Processes

Before taking any action, you need to identify what exactly is consuming your system’s resources. You can't treat the issue without a proper diagnosis. Fortunately, Linux offers many tools to help pinpoint processes that heavily use CPU or memory.

a. Using top
One of the most basic and widely used tools. Just run:

top

You’ll see a table of current processes sorted by activity. Press P to sort by CPU usage or M for memory usage. Pay special attention to the columns for PID, %CPU, and %MEM.

b. Using htop
htop is a more advanced and user-friendly version of top. It features color-coded output and intuitive navigation. Run it with:

htop

Use F6 to sort and F9 to kill a process.

c. Using ps
For a more concise command-line approach, use:

ps aux --sort=-%mem | head

or

ps aux --sort=-%cpu | head

These commands list the top 10 processes consuming the most memory or CPU time.

Terminate Unnecessary Processes

Once you've identified the culprits, the next logical step is to terminate them if they are not essential.

Use:

kill 1234

Where 1234 is the PID. If that doesn't work:

kill -9 1234

Or kill by name:

pkill process_name

Warning: Make sure not to kill critical system services.

Disable Unnecessary Startup Applications

Many services and applications launch automatically with the system. Each one consumes memory and CPU—even when not actively used.

a. Via Terminal
To view enabled services:

systemctl list-unit-files | grep enabled

To disable one:

sudo systemctl disable app_name

b. Graphically
If you use a desktop environment like GNOME or KDE, open the “Startup Applications” manager and disable the programs you don’t use regularly.

Lower Swappiness

Swappiness is a parameter that defines how aggressively the system uses swap space. The default value (60) may cause the system to use swap even when RAM is available, slowing things down.
Check the current value:

cat /proc/sys/vm/swappiness

To change it, edit:

sudo nano /etc/sysctl.conf

Add:

vm.swappiness=10

Apply changes:

sudo sysctl -p

This encourages the system to prefer RAM over swap.

Switch to Lightweight Alternatives

If you're using a heavy desktop environment like GNOME or KDE, consider switching to a lighter one, especially on older machines.
a. Lightweight Desktop Environments
XFCE, LXDE, and MATE are significantly less resource-hungry.

b. Lightweight Applications
Replacing just a few heavy apps can make a difference:
→ Text editor: Use AbiWord or Mousepad instead of LibreOffice
→ Browser: Try a lightweight Firefox version or Midori
→ File manager: Thunar or PCManFM

Clear Cache and Buffers

Linux uses free RAM for caching files, which speeds up access. But in low-RAM situations, you might want to clear it manually:

sudo sync; sudo sysctl -w vm.drop_caches=3

This clears the page cache and inode caches. Use it carefully—performance might briefly drop as the system rebuilds caches.

Tune Kernel Parameters

Tweaking certain kernel parameters can optimize resource usage.
Edit:

sudo nano /etc/sysctl.conf

Add:
vm.dirty_background_ratio=5
vm.dirty_ratio=10
vm.min_free_kbytes=65536
kernel.sched_autogroup_enabled=0

Apply with:

sudo sysctl -p

These tweaks help with memory management and task scheduling.

Use Compressed RAM (ZRAM and Zswap)

ZRAM and Zswap compress data in RAM, effectively increasing available memory without hardware upgrades.
To enable ZRAM:

sudo apt install zram-config
sudo systemctl start zram-config

To enable Zswap, edit GRUB:

sudo nano /etc/default/grub

Add zswap.enabled=1 to GRUB_CMDLINE_LINUX_DEFAULT, then:

sudo update-grub
sudo reboot

Limit CPU Usage

To prevent a process from hogging the CPU, use cpulimit.
Install:

sudo apt install cpulimit

Limit a process to 30% CPU:

sudo cpulimit -e browser -l 30

Or limit a system service:

sudo systemctl set-property service_name CPUQuota=30%

Keep Your System Updated

It might seem obvious, but regular updates fix bugs, improve performance, and patch vulnerabilities:

sudo apt update && sudo apt upgrade

For other distros, the commands may differ.

Tips

→ If kill doesn’t work, try kill -9.
→ If ZRAM/Zswap doesn’t work, check if your kernel supports it.
→ If nothing helps, consider a hardware upgrade—adding more RAM or switching to an SSD can work wonders.

Conclusion

Optimizing your Linux system doesn’t have to be difficult. Most of these steps are simple enough for beginners. The key is to regularly monitor running processes, review what starts on boot, and consider switching to lighter alternatives or updating your system.
By taking a thoughtful and proactive approach, you can significantly improve your system’s responsiveness and stability—making your Linux experience much more enjoyable.