Automation Bocks - script slowdown

The Premiere Pro ExtendScript API is not the fastest one, unfortuntely. Also, with Automation Blocks I had to balance ease of use and performance. Since project items are represented as path strings, there is a lot of conversion back and forth between these strings and the real objects, for example.
Also, ExtendScript is notoriously slow when concatenating very long strings. Here are two ways to create a text containing the names of all project items. The left variant creates a text by stepp by step appending names to an initially empty text. The longer that text becomes the slower the script will execute. The right one keeps the names in a list and only at the very end combines them to a large string. That works much faster.

@Mathias Moehl 

I started doing some performance benchmarks - please find photo attached.

You can see here how the iteration takes 0 milliseconds but the entire loop takes really long, that cannot be explained by the internal time taken in the loop.

Mathias could you please look into what is happening here?

Also I see huge slowdowns with string concatenation and lists, I'll do some benchmarks with that too.