Hey Jörg,
the extra images are being loaded from the projects which starts with “Einladung” – please try using the Excerpt field in that one, so that the tile only contains the text, without any media. This should reduce the number of images loaded on the page.
In any case, though, it really seems that the issue stems from your server’s settings: as an example, the Ikebana demo page is 4 Mb in size but loads in 3 seconds, and it’s not even hosted on a VPS or a dedicated machine – just an ordinary GoDaddy shared hosting. I recommend considering either optimizing the current server’s settings or moving to a faster one.
Sincerely,
Andrii / Satori Studio