Add an index for a heavy query
Don't invalidate the options menu from the message list as we open a
message. We also invalidate it (twice) as we show the message. It turns
out to have measurable performance impact on 2.3 thanks to ABS
upgrade our android-support library in the hopes that the newer version
might fix some perf issues with the older one
Cache our compat lookups for our message webview - (They're expensive on
older devices - and pointless not to reuse)
Stop using the old Android Market URL
Opening a folder (especially in threaded mode) does a very heavy SQL query. This method doesn't use or modify the folder object.  Don't cargo-cult the Open here.

(cketti may well tell me I'm wrong about this. Happy to listen & fix)
Make sure we always have the ID of a folder when fetching the unread/flagged count
Marking a message as read in the database is currently very expensive, especially if you have threading enabled.

Defer that until _after_ telling listeners that they're cool to show the message
Replace synchronous setting of a flag with async setting of the flag. This helps speed up message display time (anecdotally)
4.406 changelog