Okay, I saw no difference between the 2. Both scrolled lovely on my...dare I say it? Luna J3 Pro. My resolution is 360x640.
One "issue" I have is I can hold/swipe left-right and I get an extra bit of space.
This does not happen with other sites. The only difference between sites is the closing tag.
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
The "/" really shouldn't matter, right?
What I did was add "view-source:" in my mobile browser to look at your source code. I copied that line and searched, w3schools was the first option. Their code was
<meta name="viewport" content="width=device-width, initial-scale=1.0">
I had no extra space in w3 pages.
Now, I been out of the game for a couple years, but from what I understand, tags like this shouldn't make a difference if it has the / with it or not.
Otherwise, both performed much better than before, with no dissimilar performance.