Hi,
luckily I found out the reason for the strange behaviour and want to share it with you - just in case you are a beginner like me and stumble across a similar problem:

In the file names I sometimes used an apostrophe and this causes a 6 seconds delay before presentation of the first image. Furthmore I figured out, that an apostrophe doesn’t matter for the later images. However, it is crucial when used for the fist in the row.

have a good time - maranius

I have the same problem, i've tried your solution but it didn't work.
some more ideas? could the extention have something to do with it? i'm using .jpg right now.

Thijs

I allready noticed that all apostrophe in the image path should be deleted.
When I deleted the apostrophe in one of the subfolders the image load almost immediately.
Thanks for your reply!