I don't miss it because I can open a new tab but you can about this on IRC?

From what I remember the goal of a2 was stability, and after that (now) the goal would be performance.

A lot info is available here

https://wiki.mozilla.org/Mobile/Fennec

I think especially these are of interest for you

https://wiki.mozilla.org/Mobile/FeatureList

https://wiki.mozilla.org/Mobile/User_Experience

https://bugzilla.mozilla.org/buglist.cgi?query_format=advanced&short_desc_type= allwordssubstr&short_desc=&long_desc_type=allwords substr&long_desc=&bug_file_loc_type=allwordssubstr &bug_file_loc=&status_whiteboard_type=allwordssubs tr&status_whiteboard=&keywords_type=allwords&keywo rds=perf&bug_status=UNCONFIRMED&bug_status=NEW&bug _status=ASSIGNED&bug_status=REOPENED&emailtype1=su bstring&email1=&emailtype2=substring&email2=&bugid type=include&bug_id=&votes=&chfieldfrom=&chfieldto =Now&chfieldvalue=&cmdtype=doit&order=Reuse+same+s ort+as+last+time&known_name=1.9a1%2B&query_based_o n=1.9a1%2B&negate0=1&field0-0-0=component&type0-0-0=equals&value0-0-0=Autocomplete+&field0-0-1=component&type0-0-1=equals&value0-0-1=Download+Manager&field0-0-2=component&type0-0-2=equals&value0-0-2=Help+Viewer&field0-0-3=component&type0-0-3=equals&value0-0-3=NSIS+Installer&field0-0-4=component&type0-0-4=equals&value0-0-4=Preferences&field0-0-5=component&type0-0-5=equals&value0-0-5=Printing&field0-0-6=component&type0-0-6=equals&value0-0-6=Toolbars+and+Toolbar+Customization&field0-0-7=component&type0-0-7=equals&value0-0-7=Satchel&field0-1-0=product&type0-1-0=equals&value0-1-0=Toolkit&field1-0-0=flagtypes.name&type1-0-0=equals&value1-0-0=blocking1.9%2B