In terms of additional on-page CPU activity on example.com (and therefore likely on every page):
1Password +3 ms
ThinkVantage +5 ms
Enpass +15 ms
Bitwarden +25 ms
KeePassXC +28 ms
Dashlane +80 ms
Norton +88ms
RoboForm +121ms (also delays render by 115 ms)
LastPass +127 ms (also delays render by 105 ms)
NordPass +156 ms
Keeper +206 ms
Avira +219 ms
If you're in the Google ecosystem (Chrome, Google account, Android), then it syncs to your phone and works in native apps. No encrypted notes as far as I know however.
I would guess Apple's ecosystem (Safari, Keychain, iOS) would have similar functionality?
That becomes a problem when you work across both ecosystems. I use devices in both ecosystems so an independent password sync utility is necessary for me to be able to access the same set of passwords on my macOS, Linux, Windows and Android devices and within Firefox (on all 4 underlying platforms). I personally use Bitwarden which seems to have good performance in Firefox at least. The Android Bitwarden app also supports password auto-fill in native apps on Android as well (and it works on iOS as well when I had an iOS device).
I think for that use case, you have to suffer the performance penalty of a third-party password manager (original post was looking for the fastest password manager, which will almost always be the first-party one, and be tied to the one platform).
Bitwarden hangs for multiple seconds every time you unlock the vault. It loses state when you click outside of the popup, alt tab, etc.
AFAIK it also leaks the list of all your logins (or rather the sites) through their favicon caching server. To turn this off you first have to login (wtf?).
> AFAIK it also leaks the list of all your logins (or rather the sites) through their favicon caching server. To turn this off you first have to login (wtf?).
In terms of additional on-page CPU activity on example.com (and therefore likely on every page):