OH YES!, performance degradation!!!!, When the same statement need to be executed again it need to be refected from the disk, passed and executed. This is an expensive operation. You would want to have the mostly executed statements in the cache. That way you have a good cache hit. If you flush, then you would end up with a low cache hits.
May I know why would you want to flush the sqltexts?
Life is a journey, not a destination!