Comment by Glyptodon

On most of my computers keeping more than ~300 open seems to eventually lead to a crash, usually seemingly related to out of memory or something. I believe that it happens because tabs have code running in the background that wastes memory - I usually need a PC with 32gb of memory to not have Firefox occasionally crash or trigger a whole graphics stack crash (on Mac, Ubuntu family, and Arch family installs).

On Android,after about 70 tabs it starts to fail to open the tab navigator at the current tab consistently, often starting at the beginning tab, necessitating closing and reopening the tab navigator until it decides to open next to the current tab.