CPU Bottleneck: What is it? How to fix it (Beginner Guide)

I emphasize and mention CPU bottleneck countless of times when I’m discussing the software/game performance with a particular laptop. Why?

CPU bottlenecks slow down performance DRAMATICALLY runing your workflow and productivity.

Since laptops cannot have their CPUs replaced we want to prevent that from happening.

If you are ALREADY having a CPU bottleneck, there are some solutions.

What is a CPU bottleneck?

It simply means the CPU is not fast enough for the application or game (graphics settings) you are running. The CPU becomes the limiting factor! Now that’s kind of obvious right?

Not so obvious actually.

This can be a problem EVEN for very fast and modern CPUs!

It all depends on the application or graphics settings.

Example:

Let’s say you are playing World of Warcraft and you are running the game at 4k resolution at the highest graphics settings. You have the latest 4090Ti RTX on your laptop , 64GB RAM and the latest storage but it’s paired up with a Core i7?

Now although your CPU is from the latest generation (13th Core i7 or 7th gen Ryzen 7)…it will STILL be a limiting factor because the graphics settings are way too high. 

The figure below shows the maximum framerates (fps) the GPU and CPU are capable of handling in the black boxes. 

Signs of a CPU Bottleneck

• High CPU Usage with Low GPU Usage:  Most obvious sign.  If you check task manager, it will look something like this:

System Lag in Multitasking: If you notice sluggish performance when running multiple programs or doing CPU-intensive tasks (e.g., video rendering or simulation), your CPU is likely maxing out.

Causes of CPU Bottleneck

Several factors contribute to CPU bottlenecking:

• Weak CPU Paired with a Powerful GPU: When a low-end or older CPU is paired with a high-end GPU, the CPU cannot process the data fast enough to keep up with the GPU. We went over this above.
• High-Refresh-Rate Gaming: In games with high frame rates (e.g., 144 Hz or 240 Hz), the CPU needs to process more frames per second, which can overwhelm weaker processors.
• CPU-Intensive Tasks: Applications that rely heavily on the CPU for things like physics, AI, or open-world calculations can overload the processor even without the GPU being used.
• Multitasking: Running multiple programs or browser tabs in the background can also max out CPU usage, leading to insufficient CPU “resources” for your heavy tasks.

How to Fix or Minimize CPU Bottleneck

A. Overclock Your CPU

Overclocking the CPU can provide a temporary performance boost, allowing it to process more tasks per second and reduce bottlenecks. Most modern CPUs, like Intel’s K-series processors or AMD’s Ryzen series, support overclocking.

• Use tools like Intel XTU or AMD Ryzen Master to safely overclock your CPU and improve performance.

B. Overclock RAM

• Access BIOS, then navigate to navigate to the overclocking or memory settings section. Enable XMP to automatically apply a higher frequency profile for your RAM.
• Manually Adjust RAM Frequency (Optional for further tuning): Go to the DRAM frequency settings and set it to a higher value than the default (e.g., from 2400 MHz to 3200 MHz). Adjust the voltage slightly if needed (typically between 1.35V – 1.4V).
• Adjust Timing (Optional for Advanced Users): Fine-tune CAS latency and other memory timings for more optimization.Test Stability: Run stress tests like MemTest86 or use benchmarks to ensure stability

C. Lower Graphics Settings 

• Lower Draw Distance: Reducing the distance at which objects are rendered in open-world games can significantly reduce CPU strain.
• Disable or Lower Physics and AI Settings: Features like real-time physics or advanced AI often consume a lot of CPU resources. Turning them down can free up the CPU.
• Turn Off Background Tasks: Disable CPU-heavy processes like background downloads, streaming, or system scans when gaming.

D. Lower Resolution 

If despite these changes, the CPU bottleneck is still severe, then you have no choice but to use another laptop or upgrading the CPU if you have a desktop. 

Now, it’s important to keep BALANCE in mind. CPU or GPU bottlenecks often occur because there is an imbalance of power: A CPU too WEAK for a GPU that’s too powerful.

If you’re building or upgrading a PC, aim for a balanced system where the CPU and GPU complement each other. Pairing a low-end CPU with a high-end GPU or vice versa will lead to bottlenecking.

A mid-range GPU like the RTX 3060 pairs well with a Ryzen 5 or Core i5, while high-end GPUs like the RTX 4090 are better suited to Ryzen 9 or Core i9 CPUs

Are CPU Bottlenecks BAD?

Like a GPU bottleneck, a slight CPU bottleneck is not necessarily bad, especially in gaming. Many games are GPU-bound, meaning they rely more on the graphics card than the CPU.

However, if the CPU bottleneck becomes severe then it must be addressed PURELY because you are not satisfied with the performance. This isn’t as harmful as thermal throttling…it just means the CPU is being fully used and as long as temperatures are low while doing so there is no harm to the CPU.