You might have some luck with
Administration -> Appearance -> Themes -> Adaptable -> Settings -> Custom
CSS & JS
Then write this into the Custom CSS text box:
#frontblockregion {
margin-bottom: 0px;
margin-top: 0px;
}
.slidewrap {
margin-top: 0;
}
#main-slider {
margin: 0 0 0px;
}
Then perhaps try adding this to hopefully hide the div with id="frontblockregion"
#frontblockregion {
height: 0px;
}
Each of these will make incremental changes in the height of the white space you're trying to get rid of. There may be a more elegant method that gives you more control. However, one nice thing about using the custom CSS textbox is that you can add each bit of code one-at-a-time to see if it's working for you. Also you can do it safely knowing that you are not editing Adaptable itself nor Moodle, and can always "revert" by just deleting the code you're adding in the custom CSS box.
Likewise, you should be able to nudge things left or right using the custom CSS box.
I imagine that the speed of the site loading has to do with your
server's specs, server environment (e.g.
Apache, Nginx,
IIS, etc.) local network connection, etc. I don't mean to say
all of those things--just one or more factors of that nature. Also it could be something to do with your DNS setup? That's a long shot, but the lag is before the site loads. I'm just guessing. I use Adaptable on Moodle 3.10.x and I don't have that experience.
Hmm. You might want to explore the resolution of the image(s) you use in your slider? Perhaps re-exporting it/them as medium quality jpgs would make them load faster? I'm grabbing at straws. I didn't examine anything. Nope. I see that it's more of a lag before the page loads. Once it loads it's pretty quick. Maybe that's Apache lagging before serving the site? Whatever the issue, it's likely not Moodle nor Adaptable.
