Open page takes long time since upgrade to Joomla 4

Hi
Meantime i tried to find out what the problem could be and i think the problem is, after inspecting the page during loading the frontpage editor that there are a lot of image links which url-links a not valid. The curious thing is that i don't know why the images will be loaded. In my startpage there are no images which directs on these urls.

Example: Request URL: https://www.mfvaltach.at/images/2021/01/27/_spmedia_thumbs/5_oldtimertreffen_2021.jpg

In my page i do not show this image. From where are these image urls?
Who generates these directories like "2021/01/27/_spmedia_thumbs"?

When i migrate the website from Joomla 3.9 to 4 i deleted these directory on the webserver, because i didn't use the images in my page. Now after backup the images the problem looks solved.

But anyway - why does SP Pagebuilder need these image-directories (including the images) to open the frontpage editor fast?

Best regards,
Robert