If it had come out of Google or Microsoft maybe even Apple, the JRE would have been integrated into the browser much more efficiently and it would have been no slower than Javascript
But I don't remember Applets being particularly slow even back then, if you had a decent internet connection and they were written by a decent SDE
I wrote a lot of applets back in the day for little graphics experiments and such, somewhat inspired by Ken Perlin's homepage[1]. I found that it's quite possible to make applets that load fast and run fast if you care about those things while building it and do some profiling. If you pull in hundreds of megabytes of libraries and trigger a GC every second then of course it will be slow.
Same. I built a lot of animations with applets back in the day and if you avoided dependencies (other than what ships with the JVM) and your code wasn't ridiculous, you could get some pretty damn good performance out of it (minus initial load time which did tend to be suboptimal, but manageable). Applets were a pain in many ways but I think the tech gets blamed unfairly for bad performance.
But I don't remember Applets being particularly slow even back then, if you had a decent internet connection and they were written by a decent SDE