Ad blocking will improve response times on slow links by about 50%. More for really bad sites.
I'm in the process of getting a local DNS server set up at home which will help some by blacklisting ad network IPs, but it won't help over the mobile network.
And I'd rather not pay for a cloud server to use as DNS when I'm on the road, plus I think Android will use Google's DNS server if other lookups fail. I discovered this when my parent's internet stopped working for their computer and their iPhone, but my Android worked fine. Their ISP DNS was offline.
I love uBlock Origin on the desktop and thanks to you now I have it on my tablet too!
If your phone is rooted, you can just set your /etc/hosts file to send requests to ad domains to /dev/null (figuratively). That's basically what Android ad blocker apps do.
If you're not rooted, you can use Firefox for Android, which lets you use extensions like uBlock and Ghostery[0] on your phone.
[0] not an adblocker, but related, and also helps speed up sites that load lots of crud