Are you referring to the (previous.jsonlz4|recovery.(bak|json)lz4) files under sessionstore-backups? If so, you're very close: Uncompressed, they're around 40Mi

Are you referring to the (previous.jsonlz4|recovery.(bak|json)lz4) files under sessionstore-backups? If so, you're very close: Uncompressed, they're around 40MiB. Each of my tabs doesn't store much history since they're usually opened and looked at--or saved for a later date with no further navigation. I had assumed based on what I introspected from my profile directory the real bottleneck in my (ab)use was probably the JSON parser and/or my CPU. On my hardware, 8000 tabs seems to be the point where the hang detector fires, which I'm guessing is probably determined by dom.max_chrome_script_run_time? Sounds like you're telling me it's time for a CPU upgrade! Anyway, I don't know if it's an interesting data point for you, but the only time I've had Firefox's session restore fail was if I killed my X session immediately after closing Firefox, presumably before it has a chance to save state. Even then, I've been able to restore it to an earlier state using some incantation of JSON from sessionstore-backups without losing much. Again, strictly a user-induced failure. When I say that Firefox is the most stable and robust browser out there, that's not an exaggeration. If anything, it's an understatement. What's more, it's always getting better and improving. Since I see from your bio that you're a dev or contributor, I want to personally thank you for your efforts. Your work doesn't go underappreciated by us, even if we're less than kind to it. :) I remember the browser wars. Consequently, I will always use Firefox. The internals exposed to idiots like me via the profile are pretty easy to reason about. I like that.