2.9.7 ALSO have this issue , i uninstalled very less used applications from phone , and it worked fine . Using too much customised theme like icons from one theme , status bar from other and so on also make mobile behaving ODD. Xperia arc has small RAM thats the main issue .
Browser and Google...
Great great work , Misuse Feature is brilliant . Maps and Browser sometimes crashes , plz fix this , sometimes its embarrassing if someone is using google maps .
Great going developers :) , loving it
An update every week , is something SOME big names can't do . Big up to team MIUI . Great work as usual .
Clear cache wipe/dalvik
clear cache partition
install zip
reboot
Backup ur contacts and logs etc before flashing , and restore from backup menu .
MIUI made things as simple as possible