Arduino IDE starts compiling with 20 seconds delay

IDE 1.6.9 is running under Win 10 on 3 of my computers.
On my Desktop computer compiling of sketches starts about 20 seconds after clicking the "verify" Button.
This means the button changes its color to white and nothing happens. Then after 20 seconds the color of the button changes to yellow and the progress bar down right starts running. Its frustrating.

This effect appears only when changed code in the editor. E.g. when I delete some lines.

A re-verifying without changing the code is ok.

The same happens when I use the "Upload"-Button.

When I use an external Editor like "notepad++" for changing the code and use the IDE for verifying and uploading only, everything is ok.

On my laptop and my netbook IDE is running without problems.

What could I check to find a solution for my desktop computer?

Select File > Preferences > Show verbose output during: compilation to get some information on what is going on during the compilation process in the black console window in the bottom of the Arduino IDE window.

Thanks for this hint.

Since the verifying process starts approx. 20 seconds after pressing the verify button nothing is to be seen.

The attachment is a screenshot of the taskmanager. It shows that exactly nothing happens after pressing the verify button for approx 20 seconds, then the verifying process starts.

The taskmanager also shows that the "java platform SE " app starts just 20 seconds after pressing the verify button.

No idea?

Taskmanager.jpg

Try temporarily disabling your antivirus to see if it's causing the delay.

disabled Avir. But the same.
See attached Video.

After clicking verify button, the ide freezes completely for 20 seconds.

For me I found the solution with an external editor. But I don’t understand whats happening.

No attachment, sending desktop video is not possible.

I think I solved the problem.

in preferences.txt I found under "recent sketches" a list of all my sketches (more than 100) .

I changed the location for my sketches to a dircktory were no sketches are. Now there are only 5 sketches under recent sketches to be seen.

Now the freezing effect doesn't occur.

I will now check more often how many files are to be seen under "recent sketches"