[jcranmer]

By the time browsers were considering out-of-process plugins, the JVM was already thoroughly eclipsed by Flash. I think Flash's general brokenness (over half my browser crashes/hangs were caused by Flash) was the main motivation for out-of-process, not JVM's hugely broken sandbox.

[olliej]

Applets were eclipsed because of their monumentally expensive launch requirements - both time and memory.

The applets also made it hard to do a bunch of the simple games that were super popular - flash included a large amount of multimedia functions built in, and an editing environment that was geared towards interactive design.

The reason java took so long to move out of process was because the java<->browser bindings were unique to java, it did not use any of the normal plugin apis, and expected a lot of direct linkage to the host system.