Be aware that 2.2.1 is pretty outdated.
You should update to latest stable version (2.25.5 at the moment).
Maybe the update fixes the issue.
If not:
Do you get the issue just when adding notes?
Does it happen just when using the SOAP API or also when adding notes via UI?
Do you still get the timeout error when deactivating email notifications?

Do you get the issue just when adding notes? --------- yes

Does it happen just when using the SOAP API or also when adding notes via UI? ------ it happen with soap api

when adding notes via ui it takes lots of time.

After deactivating email notifications still get error.

Did you change any original source code of MantisBT?
Are there any plugins or custom functions installed?
Are there any errors or warnings in your web server, PHP or database logs?
Did you try upgrading to 2.25.5?

kinjal.parmar,

You did not provide more feedback; I am therefore resolving this issue as "no change required".

Feel free to reopen the issue at a later time and provide the requested information.