Well, that's a nice example of database abuse....
Yes, that'll have multiple effects.
First you've broken the log chain of the database and lost the ability to do point in time restore.
The re-grow of the log (and it will have to regrow immediately) will slow down every data modification in your database.
Stop shrinking your log and manage it properly.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability