Content DB Transaction logs gets filled on bulk deletion of users

Hi,

We have a Sharepoint web with around 21000 users in the SPweb.users which doesn`t belong to any sharepoint group.

So we are cleaning up these users and its running very slow and the Powershell script is throwing error message,after a deletion of 3000 users. Server has 16GB of RAM 

 DB transactions logs are getting filled. and the script is throwing errors

Error occurred at web.user.remove($userloginName)

is there a way we can delete the users with out filling the transaction log of the content db .