Your project pages are slow to load because they are just too heavy. For instance, the Casa de Pescadors page is 9MB, which really is a lot for a web page.
The reason for the pages being so heavy is that you are using heavy full-size images. Please either switch to ‘large’ instead of ‘full’ when you insert images, or actually use the galleries instead of inserting pictures as individual images (recommended).
Here is an example of a page where images are inserted as galleries. This page loads much faster as each image (‘thumbnail’) weighs much less than each of your images: Japanese Dictionary
The “galleries” I’m talking about are native WordPress galleries. You can insert them by clicking the “Add media” button above the post editor, and then selecting “Create Gallery” instead of “Add Media” on the left. See screenshot:
If you insert images as galleries, the theme will select a proper thumb size and make the pages lighter. No need to re-upload the images.
However, if you’ve switched from another theme, be sure to regenerate the thumbnails, e.g. with the Force Regenerate Thumbnails plugin. Once you activate it, please go to ‘Tools’ > ‘Force Regenerate Thumbnails’, click ‘Regenerate All Thumbnails’ and wait until the process is over.