Lists could be faster

[zadjii]

• What if we didn't pre-fetch all details, only lazy loaded them when needed?
  • The host doesn't need to read that property until it's going to show the details
    • We probably wouldn't do it immediately as needed, but like, 25 items at a time
  • The extension doesn't need to generate that property on creation. It can probably have an LazyDetails( Func<void, IDetails>) : IDetails that only constructs the data when actually read
• Similar to the above, but with context items
• EVEN MORE SO: What if we just marked a page as Initialized after the first like, 25 items? so that it's usable even as we're still fetching.

[zadjii]

[zadjii]

Just commenting out loading Details dropped it from 48s to 43s. That could just be noise.

However, dropping MoreCommands for each of these icons changed it down to 15s. That's crazy faster.

[zadjii]

Huh, a thought:

ListItemViewModel evaluates equivalency on the WinRT objects themselves. I bet:

• we could return 25 more each time FetchItems is called
• Don't InitializeProperties immediately, just stick the uninitialized viewmodel in the list
• then InPlaceUpdateList:
  • the new items will get added to the list
  • the old items (in the same place) won't be touched
  • [[acceptable]] old items in new places will be uninitialized
• then kick off a thread to start initializing them

then even if we LoadMore and fetch the same 25+25 more, we won't try to re-init the original ones

(probably not the same as just "don't pre-fetch MoreCommands et al" but just another thought)

[zadjii-msft]

look around ee1c369