To be fair, this is (relatively, compared to the age of the web) new behavior though. Even Chrome, which pioneered the "tab per process" model, didn't isolate

To be fair, this is (relatively, compared to the age of the web) new behavior though. Even Chrome, which pioneered the "tab per process" model, didn't isolate same browsing group context sites for a long time, and still shares processes on Android as a resource optimization: https://chromium.googlesource.com/chromium/src/+/main/docs/process_model_and_site_isolation.md#Full-Site-Isolation-site_per_process https://chromium.googlesource.com/chromium/src/+/main/docs/p... Firefox only released their "Project Fission" in 2021, i.e. three years after Spectre.