In practice it makes zipping around the web pretty easy and expedient. Scrolling down the New York Times homepage, I didn't notice any more load-lag than usual, but the landing spot was much more responsive and loaded quicker than usual. Anecdotal evidence only does so much, though.
Putting the Canary build (70.0.3523) to the test with Basemark resulted in a score of 501.54, with the following breakdown:
- CSS Capabilities: 57.75 percent
- HTML 5 capabilities: 96.58 percent
- Page load and responsiveness capabilities: 91.43 percent
- Resize capabilities: 75.97 percent
Standard Chrome (68.0.3440.84) scored a 489.69 with the following breakdown:
- CSS capabilities: 57.75 percent
- HTML5 capabilities: 96.58 percent
- Page load and responsiveness capabilities: 91.6 percent
- Resize capabilities: 75.97 percent.
As you can see, the numbers are identical save for page loads, which were slightly lower on Canary.
These likely aren't the type of improvements that will make a night and day difference in your daily browsing. They're more or less the type of thing that you'll notice at first and within a few days will blend into the background.
If you want to give it a run for yourself ahead of whenever Google pushes the update to stable Chrome, just enter "chrome://flags/#enable-lazy-image-loading" and "chrome://flags/#enable-lazy-frame-loading" into the Canary URL field and activate their respective options.
As BleepingComputer notes, this feature was developed with Chrome on Android in mind, but desktop users stand to benefit as well. Will it result in Chrome gobbling fewer resources when you have three windows and 60 tabs open? Don't hold your breath.