Please remove the log statements that produce the following output:

WARN info.magnolia.dam.asset.functions.DamTemplatingFunctions 16.12.2014 15:55:37 – AssetIdentifier is null or blank, return Null.
WARN info.magnolia.dam.asset.functions.DamTemplatingFunctions 16.12.2014 15:55:37 – No Asset found for assetIdentifier , return Null.
WARN info.magnolia.dam.asset.functions.DamTemplatingFunctions 16.12.2014 15:55:37 – No Asset found for assetIdentifier , return Null link.

This is completely useless in a production environment.

1) Please reduce the log priority to DEBUG, not WARN

2) Please include in the debug message the identifier that can't be found (if not null), or even better, include the current URI from the aggregation state as well.