Maybe ShellService does some kind of value caching. The other point of interest in your patch is the removal of calls to ShellService for needPin/needDefault, these values are later used in the screen targeting expressions. I guess it's conceivable that the ESM calls early in startup previously caused ShellService to cache something, so it didn't need to be recomputed during the page load test when screen targeting was evaluated. So, you could try making dummy ShellService calls somewhere in AboutWelcomeParent, as you did with the static import.
Bug 1859583 Comment 9 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Maybe ShellService does some kind of value caching. The other point of interest in your patch is the removal of calls to ShellService for needPin/needDefault, these values are later used in the screen targeting expressions. I guess it's conceivable that the ESM calls early in startup previously caused ShellService to cache something, so it didn't need to be recomputed during the page load test when screen targeting was evaluated (saving ~75ms). So, you could try making dummy ShellService calls somewhere in AboutWelcomeParent, as you did with the static import.