[Updated] Google is Testing a “Never-Slow Mode” for Chrome

Update on 06-FEB-2019:

Chrome to Delay Low Priority Tasks to Reduce Memory Usage

Update on 03-FEB-2019:

I spotted another code commit today, (this time adding the flag for real I guess) with a couple of typos in the flag description. This time, the commit log has some additional details that give a into what is coming:

Currently blocks large scripts, sets budgets for certain resource
types (script, font, css, images), turns off
document.write(), clobbers sync XHR, enables client-hints
pervasively, and buffers resources without Content-Length set.
Budgets are re-set on interaction (click/tap/scroll). Long
script tasks (> 200ms) pause all page execution until next

Caps do not apply to workers and size caps are lifted for
resources loaded from Service Worker Cache Storage.

Current caps; all values are wire (transfer/compressed) size:

Per-image max size:        1MiB
Total image budget:        2MiB
Per-stylesheet max size: 100KiB
Total stylesheet budget: 200KiB
Per-script max size:      50KiB
Total script budget:     500KiB
Per-font max size:       100KiB
Total font budget:       100KiB
Total connection limit:   10
Long-task limit:         200ms

Chrome was very simple and lite when it first launched. Over the years, it added a lot of features and Chrome’s memory requirements also grew with it.

I’ve seen a lot of people requesting a “Lite Mode” for Chrome. To be honest, it is in my wishlist too.

I am not sure if this experimental feature that I spotted today is something that we can call “lite mode”, but this is the closest I’ve seen in Chrome.

The commit log says:

“Never-Slow Mode”


Adds --enable-features=NeverSlowMode to support blocking large
scripts, turning off document.write(), clobbering sync XHR, enabling
client-hints pervasively, and blocking resources without
Content-Length set.

I could find the flag description from within the code:

“Enable Never-Slow Mode”;
“Enables an experimental mode that restricts resource loading and ” “ processing to deliver a consistently fast experience. WARNING: “
“may silently break content!”;

So, this feature does not cut down Chrome’s memory usage and make it lite, but it does that to the page that you are loading. If you open a web page with a lot of large scripts or other fancy stuff (my term of things that I don’t understand), Chrome will stop all that and try to load the page faster.

This of course is in the very early stages of development, if not testing. I’ll definitely keep an eye out for this feature when it is ready for us users to test.

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