windows 10 - CPU Usage jumps down from 100% to normal levels after opening task manager

I've been searching for an answer to this and have tried all the options described in similar questions.

My CPU usage is at 100% when I open the task manager and then jumps down to regular levels once I open it.

I've scanned for malware using Malwarebytes, ADWcleaner, ESET online scanner, windows defender, and they have all come back clean.

I also used process explorer to find out what process was causing this but couldn't find anything out of the ordinary.

Answer

Task manager has a lot to do when it loads. It has become quite complicated in recent years.

The task manager has to scan through hundreds of processes

• For each process
  
  
  
  
  • Get process name
  
  
  
  • get executable name
  
  
  • PID
  
  
  • Memory usage - Working set, private, etc
  
  
  • various other information
  
  


• Get the current statistics for each process (Process tab)
  
  
  
  
  • Memory Use
  
  
  • Disk use
  
  
  
  • Network use
  
  
  • Group processes by executable and get memory totals and per process
  
  


• Get the historical statistics for each process (App History tab)
  
  
  
  
  • Memory Use
  
  
  • Disk use
  
  
  • Network use
  
  



• Get current system statistics (Performance)
  
  
  
  
  • CPU usage
  
  
  • CPU information
  
  
  • Disk usage and utilisation
  
  
  • Ethernet/Wifi addresses and utiilisation
  
  
  • Graphics cards details (memory, type, shared memory) and utilisation
  
  


• Startup tasks from various locations



• Logged in users and processes


• Services details
  
  
  
  
  • Name
  
  
  • State - running, stopped, etc
  
  
  • PID
  
  
  • User, etc
  
  

And then it has to build and populate the UI with all that information. It could be loading up various tabs at the same time as grabbing information from the system.

In order to do it quickly it could well be using multiple threads to get all the information from the system as quickly as possible. It does have a substantial amount of information to grab and (for me) still loads in under a second or two. Granted some information is duplicated across the Process and Details tabs, but there's a lot of rearrangement and processing to group and display and collate information for the Process tab.

I don't consider this a sign of malware.