Probably just disabling (disable in start up) Dell Support Assist would have fixed it.   On some models, there is a Support Assist app that is used in the POST (Power On Self Test) and hardware diagnostics,

Having said that, I have a dual boot (two Win 10 installations) on my Inspiron 15 5577, one with the full Dell image and another without Dell support assist that I use in my recording studio and it works OK.

Following below steps may provide a workaround:

1. Browse Control Panel
2. Select System and Security.
3. Select System
4. Select Advanced System Setting
5. Under Performance, Select Setting 
6. Select the Advanced Tab.
7. Select Change
8. Set the minimum to the amount of System Ram installed.
9. Set the Maximum to double the amount of System Ram installed.
10. Select Apply
11. Select OK
12. Restart the computer.

This process increases the size of the Pagefile that Windows uses to ensure that enough storage space is allocated to the Operating System.

I've done all the above, and over the last few years (YEARS!) have tried all sorts of things to try to get my Inspiron to work properly. Nothing works for long. I'd blamed Microsoft because most of the time it's their updates that are using 100% disk and stopping other things from running, but it could just as easily be the Malware or another background process. I will admit that it slowed down massively after an update just a couple of months after first using the laptop, which is why I assumed it was Windows itself that was the problem. I have a much older Dell Latitude that has the same amount of RAM and also runs Win10 (updated to the same level) and that flies. Therefore I have to conclude that there is something wrong with the Inspiron (13-5378). Possibly a device driver. A clean boot doesn't help though. I put the latest BIOS update on this morning. No improvement.
Dell have just built a poor machine. . .

I have the same issue and I have been trying to fix it for a year.

I have the Inspiron 15 3000 series with 8gb ram and 1tb HDD. 

Ive tried resetting the virtual memory as above, I've tried disabling different services including superfetch and sysmain. Also tried disabling antivirus temporarily and all the other stuff. 

I finally gave up last night. I followed countless blogs/instructions online, community forums and device support itself but to no avail. Constant 100% disk usage. I've only had the device just over 2 years and can't afford to go and buy new. Does anybody know if I add an SSD to the V.2 slot if that will solve the issue? I've been thinking about it but can't afford £80 if it's not going to work. 

Did anybody find a successful solution for the issue? 

Thanks

We need the model number (Inspiron 3501, 3593, etc.) to advise you on the answer.

How about Precision M6700 with Win10 21H2 installed and Precision 7710 with Win10 21H1 installed. The first PC has 16GB of RAM and becomes non responsive at 100% disc utilization and the second is marginally better with 32GB of RAM.  There is something really wrong here....unless I wait 15 minutes for the both PC's to stabilize on startup..... Windows Malware Protection could be an issue, I have not been able to isolate to an App yet.  And once it goes into "GULP MY RESOURCES" mode, I have to walk away for 5 to 10 minutes.

Update: I've finally decided to bite the bullet and upgrade the laptop from 4GB to 16GB RAM. As expected, some software opens a bit faster, and Task Manager now reports memory usage peaking at about 18% (running one application at a time, usually). However, nothing else has changed. The HDD is often whacked out at 100% with nothing happening (with System, Search, Antimalware or one of the Update possé taking top spot). Sometimes I can hear the HDD clicking away. Sometimes it's silent yet the listing still says 100%. Often it seems to freeze and even Task Manager won't update its display.
Almost every time I start to type into the Taskbar Search box (or Search in an Explorer window), there's a long delay before the system realises what I'm doing and starts displaying the characters. Usually it misses out the first few letters, so I have to go back and re-type them. This is a dysfunctional system.
Given that this has had a "clean" install with only the required device drivers added, I have to conclude that it's either a driver issue, or (more worryingly) there's a hardware problem.
On other forums, I've been advised to replace the HDD with an SSD. I'm sure this will help as if it's genuinely trying to access the drive so much, fitting a much faster SSD will minimise the effect. But at the end of the day, this is just treating the symptoms, not the root cause. My other (older) Dell laptop with only 4GB RAM and a slower HDD runs Win10 with no problems at all.

I have the same problem. 

Update: after a few weeks with 16GB, I can confirm that the issue is exactly the same. It still struggles whenever too many background processes are going (usually Win update services - and there are many of those!). I tried pausing the updates for a couple of weeks but Windows ignores that setting and the updates carry on running anyway. But as I've said before, that's not the real problem. That's just making it worse. The real problem seems to be some driver or hardware issue with the Inspiron itself. It freezes for several minutes (maybe up to an hour) and I just have to walk away and wait. Every couple of weeks it decides that the HDD is at 100% with just the System process using it (but NO SOUNDS COMING FROM THE HDD ITSELF). This suggests either a HDD driver issue or a faulty HDD or interface. My old Latitude (still with only 4GB RAM) has none of these problems and runs fine.

So, Dell: can you come clean, own up to there being a problem with this model and help me fix it? Would another HDD help (it's at least easy to test, once I've bought a replacement)? Or is it an issue with the motherboard and I'll just have to throw this thing away?