Yes, my recollection of the Squeak browser plugin was that the performance was indistinguishable from running regular Squeak, several orders of magnitude better than SqueakJS. And the startup time was vastly better than any Java plugin code.
However, if you were on dial-up, and your browser didn't already have a cached copy of the smalltalk image, then you were in for a quite a wait. (Though no doubt this could have been addressed - there were people arguing at the time for the creation of a much smaller Squeak image, but a combination of the lack of a clear goal to motivate this work, and the fact that for most existing users it was a non-issue, meant that nothing came of this within the timeframe where it might have made a difference.)
But it may be that this is all moot, because it could be argued that any browser-plugin deployment model would ultimately fail.
I used the Squeak browser plugin with a class of university students in the late 90s - it worked really well. Native speed, much more interactive GUI than the browsers at that time, and I could update their essentially desktop app between classes and not have to get it reinstalled by IT.
I did have to do some persuading to get IT to install the plugin in the first place though.
It was doomed tech in hindsight though, together with all the other plugins.
However, if you were on dial-up, and your browser didn't already have a cached copy of the smalltalk image, then you were in for a quite a wait. (Though no doubt this could have been addressed - there were people arguing at the time for the creation of a much smaller Squeak image, but a combination of the lack of a clear goal to motivate this work, and the fact that for most existing users it was a non-issue, meant that nothing came of this within the timeframe where it might have made a difference.)
But it may be that this is all moot, because it could be argued that any browser-plugin deployment model would ultimately fail.