The current time stamp mechanism in simfactory creates files with a scheme "timestamp-NUMBER", where NUMBER denotes the time. Looking for such files requires iterating over the directory.
Instead, we can use a fixed file name, and use the file creation time as time stamp. (We can additionally write the time stamp into the file, probably in a human readable form.) Accessing this time stamp is a single "stat" operation that should be quicker.
This method has the additional advantage that the time stamps always have the same file name.