Container Tabs are completely orthogonal. A site loaded in a tab which is contained in this way cannot access your global cookie jar, for example. If you visit a site with a Facebook Like button on it, then Facebook will not receive the same cookie from you that it would have received if you had loaded the site in a non–contained tab. This is true whether or not the site has been given it’s own process to live in. The converse is also still true; non–contained sites still have access to your global cookie jar even if they’re isolated in their own process.
Putting sites in their own process mitigates against Spectre–like attacks, but it doesn’t do anything for higher–level problems like third–party cookies.
I think they are complementary, since one is about browser site isolation, and one is about process isolation on the computer.
Using temporary containers, multi-account containers, site isolation, along with a number of other privacy/security addons such as Umatrix, LocalCDN, and many others, I have not noticed any slowdown.
So far it seems to work fine for me too. Can you share you list of security/privacy addons? I've used Umatrix but never heard of LocalCDN. Was wondering what other gems you may have found.
Here is a complete list of security/privacy addons I am using, a small number of which I have disabled, as I regularly toggle them depending on what I am doing at the time
Enable Strict Enhanced Tracking Protection setting, this turns on Dynamic First Party Isolation which is the native version of what Temporary Containers is aiming to do.
Based on the processes I'm now running, it seems that tabs for the same domain but in different containers do (as one might expect) count as separate origins for the purpose of creating one process per origin.
So they do different things, and interaction between the features appears to work without issues.
Putting sites in their own process mitigates against Spectre–like attacks, but it doesn’t do anything for higher–level problems like third–party cookies.