Does tampermonkey performance worse on manifest V3 than it's on V2?

[yeezylife]

Efficiency is lower for extensions like ours that need to process every navigation because MV3 disallows persistent background scripts, which means it will restart hundreds of times a day wasting resources much more than in MV2. No one in Chrome team has ever measured the impact, they just believe in an idealistic notion.

MV3 userScripts API doesn't support regular expressions, so extensions have to run all such scripts in all tabs and frames, and perform the check there, which means that every regular expression will be recompiled again and again without caching, thousands of times each day. The scripts may be very big, so megabytes of code will waste the CPU time and battery without being actually used.

MV3 userScripts API doesn't support smart blacklists offered by Violentmonkey, see the previous consideration minus the regular expression compilation.

MV3 userScripts API doesn't support setting GM_setValue separately, so we have to re-register the entire script and embed its storage data alongside the code, because GM_setValue/GM_getValue are synchronous and the data must be present at the moment the script runs. Re-registering is a complex operation inside the browser, so if we do it every time the script changes a value via these GM functions, the overhead will be staggering. We could throttle these updates, but only by a few milliseconds, otherwise when the script reloads the tab the old incorrect data will be loaded.

If we don't use the very limited MV3 userScripts API, we can't ensure the scripts will run at document_start:
"synchronous page mode" option won't be available as MV3 removes webRequestBlocking
the background script will need 50ms - 500ms to start and load the scripts every time navigation occurs after a pause of 30 seconds, which may easily happen hundreds of times a day.

The above is a quote from the author of violentmonkey. It sounds like that script management implementation on manifest V3 still has many limitations.

[jb222]

The above is a quote from the author of violentmonkey

Could you provide a link to the original post? Thanks.

[yeezylife]

violentmonkey/violentmonkey#1934 (comment)

[Owyn]

"synchronous page mode" option won't be available as MV3 removes

wait, there's such a mode?!

I thought when greasemonkey made that big update which introduced async GM.getvalue and broke all the old scripts - they said that userscripts are no longer guaranteed to run without a random delay when you want them to since it's all non-blocking now

I'm using Firefox tho

[derjanb]

wait, there's such a mode?!

In MV2 it was "Inject Mode: Instant" and now "Content Script API: UserScripts API Dynamic" allows script execution at real document start.

[Owyn]

Thx a lot for that setting!
You've just saved my userscript https://github.com/Owyn/Universal_Dark_Theme from flickering on page-load from white to black annoyingly