Hello:
I have noticed recently that there's extreme CPU usage even when LogView is completely idle, that is more than 50%, not having any logs open, not having any applications running.
What's going on?

I normally monitor just one file name. Yes, the directory is monitored for changes, but at the moment of the screenshot, no files were being written, no applications running. I intentionally deleted the file from the workspace to check if it's related, but the CPU usage remained the same. It did not change upon restart.

If you are using a directory monitor, what happens if you kill the directory monitor?  Are you searching the directory recursively?  If so, how many child directories are there?  Is the directory local or remote?

If the CPU remained high after restart, were you monitoring the directory after restart?  Is LogViewPlus configured to automatically open the last workspace?

Yes, it monitors recursively a few dozens of child directories for the most recent log file. Do you imply the monitoring causes this? How can I exclude older directories from monitoring?

LogViewPlus polls the directory for changes.  Depending on the number of files and directories being monitored, it might cause a problem.  What happens when the directory is not monitored?  Does performance improve?

There is no way to exclude older directories.  

Yes, this helps, thank you. 
It would be great to be able to filter monitored directories by mask.

Glad that helped - thanks for letting me know.  

Filtering by mask is a good idea.  This is something we could look into for a future release.