CPU 45% idle and Activity monitor only justifies less than 4%

[aicul]

My iMac has recently started to slow down. So I checked various blogs and tried the usual actions. To no avail.

Now I have found a blog that says to look at activity monitor and check the CPU use. Here I notice something real strange.

My iMac CPU is typically 40-45% idle which would indicate that there are processes ongoing for at least 50%. Well I can only see 2.5% (Activity monitor), 0.5% (Dock) and 0.1% (LoginItem) and 01.% (SystemUIServer). (note values update constantly but do not vary greatly).

This is strange as there should be some relationship between listed processes in Activity Monitor and the % idle....

(Note: there are no other "paused" users logged-in.)

Can anyone suggest how to interpret this, and whether this could be a sign of the slow down ?

thanks

presently

 

[aicul]

I've worked on this and here are some steps I have taken;

- I googled more and think that this is not the distnoted process issue (google distnoted for more info)

- A repair of the disk was requested by Disk Utility but it did not seem that involved

- I ran ONYX all cleanup, all purge, all repair, all everything

All in all I now have 98% idle... much more reasonable.

But I would like to know what was the cause... I don't like doing and not understanding.

Any input welcome