While opening a usual new tab (Ctrl-T or click at the plus sign) works fine, opening a new container-tab (whether using Firefox Multi-Account Containers add-on or click and hold at the plus sign) causes Firefox to freeze for almost a minute, if not longer. When Firefox is freezing, I notice one of my 4 CPUs has 100% usage. The freezing doesn't happen all the time, just when I open multiple container-tabs (like 4 or more tabs). I'm pretty sure It's not about container-related add-ons, because I already tried disable them all (Firefox Multi-Account Containers, New container tab, and Search and Switch Containers) and It didn't help. For now my dirty solution is to restart my laptop. Could someone help me with this? P.S. As you can from the attached picture, the 100% usage of CPU is caused by firefox process (glowing purple). Update: Now I can avoid this bug by opening a usual new tab with Ctrl-T and then use "Search and Switch Containers" add-on to switch to the container I desire. This gives the normal performance.