Inspiron 15 Extremely Slow

If this laptop is brand new, it is probably downloading and installing Windows 10 updates.

Thanks for your reponse.  the laptop is definitely not downloading anything.

Return it for a refund.

 " As an example, I used the Detect This PC option on the Dell Support website and it took over 10 minutes for it to respond "

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10 minutes is a very long time. You were able get into your Dell Product Support page and downloaded / installed any drivers onto the system ? Is the computer brand new ( per nyc10036)?  What is the exact Dell model number and version of windows? Example: Dell Inspiron 3543 windows 10. If you don't know, type msinfo32 onto search box, stroll down System Model, you should see it now. Lastly, boot into safe mode to see if computer is lagging or going slow. 

Using safe mode to troubleshoot problems on your Windows 10 PC

https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode

I have the same problem for the exact same model Inspiron 15 3531. We bought this laptop new some years ago. Early in its life the speed just dropped off terribly.  Out of warranty so we have been on our own. After trying multitude suggestions, including wiping and reinstalling, I have found no answers yet. It is painfully slow doing ANYTHING: booting, opening any program, opening Task manager, opening browsers, surfing ... etc etc.

There is no way Dell could reasonably believe this speed is tolerable.

Please share any solutions you find. I will do the same for you.

Let's hope for the best. - T

@lifebird 

I have old laptops (9+ years old) myself.  

I have switched to SSDs from traditional hard drive even though the laptops had the faster 7200 rpm hard drives. I suspect your laptop probably has the even slower 5400 rpm hard drives.

Also 4 GB of RAM.

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This is bonkers but it happened to me.  I spent 2 days troubleshooting my laptop and pouring over the forums.  Nothing worked.  Then I randomly looked at the power plug and it was slightly out of the socket maybe 1/8 inch.  I pushed it in and boom it worked as normal.  It was receiving energy but not enough so it shifted the processor into some low power mode.  That 1/8 inch cost me 2 days of work.

The Inspiron laptops detect which type of power adapter is attached to the computer. (Center pin of the power jack). If the computer detects a power adapter with a unsuitable wattage output or is unable to detect the wattage at all, the laptop will operate in a reduced performance mode. While in this mode, the processor will not exceed a certain frequency and the battery will not charge, or will charge very slowly. Usually a damaged jack, power connector, or cord will cause this to occur.

I think there are 3 possibilities. 3rd one is optional though.

1. Does your laptop temperature gets very high after doing some heavy work in less time? If yes than download a software call HWMonitor. Install it and run HWMonitor. And than run anything that uses your processor heavily. Now check if your processor temperature is above 70 Degrees Celsius. If yes than maybe we have found the culprit. Your laptop is slow because your processor is slow. When processor gets heated up it reduces it's performance to maintain the temperature.

Solution is : Apply new thermal paste on the processor. If you know how to do it than it's good. But if you don't than better go to laptop service center. And don't forget to get your own good quality thermal paste. This will reduce the temperature considerably. And you might notice the boost in the performance of your laptop.

2. Second issue is RAM. Nowadays 8GB RAM is necessary. Try upgrading your RAM.

3. 3rd but it's optional. About your HDD. Is your HDD very old? Try upgrading to new one. Or better get a SSD. But this is totally optional. Don't bother this solution if you have tight budget.

Thanks for your reply.  The  unit is under NO load so I  don't believe it to be a thermal issue.  

the  previous poster  suggested  that  it  was the wrong power adapter so I am pursuing that right now.

Very Interesting.  Thank you for your reply.  The power adapter is an HP product so not the one that  came with the laptop. I will try to find at least a Dell adapter with more wattage/capacity.  I will keep you posted.

It is 100% the charger. Watch the cpu frequency when you plug it in and then when you unplug it.