Freezing server for 10-20 seconds

Hello.
I’m DarkRP server owner, and I have a problem.
Some players on my server sometimes be kicked with reason: Client left game (Steam auth ticket has been canceled)
This players be kicked after 10-20 freeze (lag) seconds, after kick my server was unlagged.
Why is this happening? Why my server is lagging before kick some players with this reason?
Do you have this problem?

P.S. I know this error, and i don’t know why my server is freezing before kick some players.
P.S.S. Sorry for my bad English language.

-bump-

Are you running the server on your computer? Is it a dedicated server? If it’s running on your computer you should make sure you don’t have many applications running in the background

I have a dedicated server.

Are you running it from your house or did you buy it? If you bought it maybe it’s an addon on the server causing a problem. Otherwise you may need to contact the people you bought it from

I bought it.
What could it be? Timer, or other function?