I also noticed this and stopped using DDG because of it. My assumption was just that scaling is hard and DDG wasn't as good at it as Google is.
I just tested this myself and, while google loads its DOM content almost twice as fast as duckduckgo for me (1.2s vs 0.7s), that's still way within a reasonable time for a webpage. For comparison, youtube took me 3.5 seconds to load the DOM content.
That said, it may still be some difference like browser caching, or maybe android even does that. My tests were on a Windows PC using chrome.
You could try doing a traceroute from your mobile phone to both Google and DDG.
The number of hops and latency you see in traceroute may help you figure out what kind of CDN and global server load balancing that DDG is doing versus what Google is doing, and thus why their respective web pages are the speeds they are.
Google serves content from a data center near you, others just from 1-2 central servers. You cannot beat the shorter connection.
That's btw Google's trick, from the very beginning. It was not pagerank or any better algorithms, it was purely massive investments getting into all the data centers worldwide.
Duckduckgo is slow for me as well. I stopped using it because of this.
If you're looking for an alternative to Google that is faster than duckduckgo, try Bing. It is still slow, but faster than duckduckgo.
Could be that Google is paying your ISP for traffic prioritization.
Google has more money and resources than duckduckgo. I suffer through duckduckgo because I rather anyone than Google. At this point, I might start giving bing a try.
In my case,
DDG: 4-5 seconds.
Google search: 1-2 seconds.
Carrier - Airtel (4G) in India.
I would guess more of Google's landing page is cached, and it's a smaller page.
I'm getting Google in 0.5-3 secounds, DuckDuckGo in 3-4 secounds, StartPage in 2 secounds. USA 4G 3:30AM
On another note, both Google and DuckDuckGo seem to link directly to search results but actually redirect your broswer to capture the link you clicked. StartPage links directly to search results.
I've asked DuckDuckGo about this and they can't provide a sastifactory answer. Maybe someone could clue me in why that redirect is nessicary, but until then I consider them untrustworthy.