problem with phoenix viewer

Yes...I have a problem. Maby some of you is smarter than me and could help.
Well lately "doesn't arrive" to me any of  my groups notices (including some of subscribomatic group messages).  I use (I'm a big fan of) Phoenix viewer. I know that LL updating something but on phoenix viewer blog its written : "As a result, moderators of large groups with more than 10,000 users are unable to load the group member list. This leaves users unable to manage group memberships on anything other than the Linden Beta. LL has also released some new notifications to the server that some old versions of Firestorm and all versions of Phoenix will not recognize. This leads to error messages that say, "Your version ofviewer namedoes not know how to display the alert message it just received." 
So I think that my problem had nothing in common with that update.

Recently I've noticed that the information sent in subscribomatic messages shows me but I didnt receive an attachment (as is the case with one of  blogger group I'm in).
Well in phoenix viewer blog I saw a Firestorm Phoenix-like interface mode and I say YEY, but when I finally install it I have lag as hell.
Any suggestions and help are welcome.