I know that this might vary from case to case, depending on which PC and which app I have open, among other factors. However, I noticed that with all that I had open, regardless of the apps or games running, when the PC starts to slow down or lag, the CPU or memory is not used at 100%, but stays between 70% and 90% depending on the situation. What could be the reason?
In: Technology
Could be a various amount of reason: is the workload not able to efficiently use multiple threads, is the storage device that programs are trying to use the limiting factor, or other issues.
Memory at 70% and 90% is considered heavy usage, the system has to swap in and out a lot of pages from virtual memory, which is a file on your hard disk. Unless you have VERY fast m.2 SSD, it’s going to slow things down a lot.
CPU and Memory are only two resources that can be scarce. It can also be waiting on network, disk i/o, graphics processing, or waiting for locks on resources to be freed up.
70-90% is pretty heavy usage
It’s possible the apps at fault are unable to use multiple CPU cores (multi-threading) so they are pinning (maxing out) a single CPU core.
If you have 4 cores, and one is completely pinned Windows will only report your CPU as 25% utilized.
Your hard drive is also commonly a bottleneck. If you see very slow performance when loading apps, or running an application but CPU usage is low then it’s possible that your Hard drive is unable to keep up.
The single greatest performance improvement in PC hardware these days is replacing a spinning hard disk with an NVMe SSD
Having less memory being available may affect the efficiency of CPU instructions. If I asked you to put away boxes on a stack of shelves, then remove the boxes that have a certain label later, it would be more efficient for you to do if you were working with an empty stack of shelves than if you were working around boxes placed randomly on shelves that you couldn’t touch. Also, these days, CPUs have multiple cores and multiple threads that can perform multiple functions simultaneously. But whether your software can take advantage of the simultaneous processing is a different story. Some processes need to be performed consecutively along one thread. If the process is using 100% of one of your CPU cores, but you have 4 cores, you may see on your task manager that just over a quarter of your CPU is being utilized eventhough the software is lagging from it maxing out one of your cores. If you’re on Windows and open the hardware resource monitor from the performance tab of your task manager, it will show you how each CPU core is being utilized.
CPUs can’t run on 100% indefinitely because they generate heat. This is also why your computer’s fans start to go crazy when you are running a CPU-intensive process. The firmware may have decided that 70% is as high as the CPU can go right now, and so that’s what your computer is stuck at for the time being.
Do a task requiring 10% of your focus. Now do 7 of those simple tasks at the exact same time. It isn’t 7x harder, it’s 20x harder.
The cpu has to clear and unclear caches, transfer data between components, wait on the disk even with SSDs.
Although it isn’t working that hard when it has a task, it’s interns are running all across the office gathering stray papers. The boss must wait. You must wait.
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