> I had to disable e10s because whenever I switched tabs the page would sometimes be replaced indefinitely by a white screen with a big loading indicator.
I'm pretty sure I know what loading indicator you're talking about, though I don't have a screenshot handy.
Basically, this is because one of the other tabs is hogging the rendering process. Since the Firefox UI[0] is controlled by a separate process under e10s, it's still responsive while the other process is rendering webpages. So, you're able to switch tabs before there's something there to switch to.
Without e10s, under this situation, the Firefox UI will be unresponsive while the tab is rendering web content (the browser will appear to lock up). That doesn't necessarily mean the tab will always be fully rendered by the time you're able to switch, but the loading indicator was added to e10s specifically because multiprocess mode makes this situation more likely to occur than under single-process mode.
If you want to see what I'm talking about, try visiting an Amazon product page both in an e10s window and in a non-e10s window[1].
[0] Confusingly referred to as the chrome, a name that predates the browser with the same name
[1] Unless they've fixed it recently, there's a longstanding, known "bug" that's caused by Amazon "prefetching" the content of all links on an Amazon product page. This Javascript is included only when the page is loaded in Firefox, and it's rather redundant, because the content is still re-fetched when the link is clicked. Unfortunately, Amazon hasn't fixed this, and I don't think there's much Mozilla can do about it.
I'm pretty sure I know what loading indicator you're talking about, though I don't have a screenshot handy.
Basically, this is because one of the other tabs is hogging the rendering process. Since the Firefox UI[0] is controlled by a separate process under e10s, it's still responsive while the other process is rendering webpages. So, you're able to switch tabs before there's something there to switch to.
Without e10s, under this situation, the Firefox UI will be unresponsive while the tab is rendering web content (the browser will appear to lock up). That doesn't necessarily mean the tab will always be fully rendered by the time you're able to switch, but the loading indicator was added to e10s specifically because multiprocess mode makes this situation more likely to occur than under single-process mode.
If you want to see what I'm talking about, try visiting an Amazon product page both in an e10s window and in a non-e10s window[1].
[0] Confusingly referred to as the chrome, a name that predates the browser with the same name
[1] Unless they've fixed it recently, there's a longstanding, known "bug" that's caused by Amazon "prefetching" the content of all links on an Amazon product page. This Javascript is included only when the page is loaded in Firefox, and it's rather redundant, because the content is still re-fetched when the link is clicked. Unfortunately, Amazon hasn't fixed this, and I don't think there's much Mozilla can do about it.