Dell has an article titled Troubleshoot and fix a Dell computer that is running slow, and Microsoft's performance guidance is the checklist for any desktop: restart, install pending Windows and driver updates, close programs and browser tabs you are not using, limit startup apps, free disk space and run one antivirus scan. An OptiPlex 7020 is a business machine with a Core i5-14500 or i7-14700 and DDR5 memory,
so it is fast on paper, and a slow one is usually slowed by software: a management agent, endpoint security scanning, a full drive or too many startup programs. On a company-managed unit, do not remove security or management software yourself; ask the IT team. Find which resource is at the top in Task Manager before spending anything, and if the disk sits at 100 percent at idle, run Dell's diagnostics on the drive.
Differential
Likely causes of “Dell OptiPlex 7020 is running very slowly”, and how to tell them apart
- 1
Too many startup apps and open programs
What separates it The desktop is slow right after login because of too many startup apps and open programs
How to confirm Microsoft names startup apps as a cost; disable those you do not need in Task Manager, Startup apps
- 2
Management or security software scanning
What separates it The disk and processor are busy with a security or management process
How to confirm Ask your IT team; do not remove company software
- 3
A nearly full drive
What separates it Everything is slow and Storage shows little free space
How to confirm Free space with Storage Sense; Windows needs room to work
- 4
Pending updates
What separates it The desktop has been slow since an update was postponed
How to confirm Install Windows and driver updates and restart, as Microsoft advises
- 5
Malware or a failing drive
What separates it Disk sits at 100 percent when idle after a scan
How to confirm Run a scan and Dell's drive test; if it fails, back up and book service
Before you touch a setting
Record this first — changing settings destroys the evidence
- The OptiPlex's Service Tag, form factor, memory and Windows version
- Which resource is at the top in Task Manager and how much drive space is free
- Whether the machine is company managed
Try in this order
0 of 7 completedRestart
ReversibleChoose Restart rather than Shut down, because a full restart clears processes that have stalled and reloads the drivers.
Install updates
ReversibleInstall updates, by running Windows Update and Dell Command Update for drivers and BIOS, and then test again to see whether it helped.
Find the heavy resource
ReversibleOpen Task Manager, Processes, and sort by CPU, Memory and Disk in turn to see which program is using the most of each.
Limit startup apps
ReversibleOpen Task Manager, Startup apps, and disable what you do not need, so fewer programs compete for resources after every login.
Free drive space
ReversibleOpen Settings, System, Storage and run Storage Sense to clear temporary files, then check how much free space is reported.
Scan for malware
ReversibleScan for malware, by running Windows Security's full scan, or the company's tool on a managed machine.
Run Dell diagnostics
ReversibleRun Dell diagnostics, by tapping F12 at the Dell logo and testing the drive and the memory.
Model-specific
What is true of this model and not of its siblings
- Processors
- Core i5-14500 or i7-14700, per Dell's owner's manual. A slow unit with either is more likely a software or drive problem than a processor problem.
- Repair cost
- Slowness is usually startup apps, storage or updates and costs nothing to fix. RAM replacement is $59 to $89 in labor and an SSD replacement $99 to $179, per BadgerLayer's 2026 PC repair guide.
Stop boundary
When this stops being a self-service repair
- !If Dell's drive or memory test fails, back up your files and contact Dell Support
- !If management software is the cause, contact the IT team that owns the machine
- !If the desktop is slow only when hot, see the overheating page
Evidence ledger
Sources behind this answer
Dell's slow-computer troubleshooting guide.
Startup apps, free space, updates and restarts.
Storage settings, Storage Sense and removing apps.
The Dell OptiPlex business desktop line.
Exact questions
Common questions
Does sleep versus shutdown change the speed?+
A tower left running for weeks can slow down as memory fills. A full restart clears it, and a weekly restart is a cheap habit for a desktop that stays on.
Does a management agent slow a business desktop?+
It can, especially during a scan. If slowness follows a schedule, tell your IT team the time it happens, since they can move or tune it.
Is it worth adding memory?+
Only if Task Manager shows memory near full in normal work. Check the maximum and slot count for your form factor first.
How do I tell a drive fault from a slow drive?+
Dell's diagnostics test the drive without Windows. A test that fails is a fault; a pass with a full disk in Task Manager is a load problem.
Does Dell have a slow-computer article?+
Yes, titled Troubleshoot and fix a Dell computer that is running slow.
Why is a business desktop slow?+
Management, encryption and security software can use a lot of resources. Ask the IT team before removing anything.
Can I add memory?+
The OptiPlex is described by Dell as serviceable inside, and it uses DDR5. Check the maximum and slot count for your form factor first.