I identified one performance problem with DNN 6.2.  In the database, the tab view calls a UDF twice to remove some characters '&? '  from the tab name.  Calling a UDF in a view is generally a performance killer. My view is named dnn_vw_Tabs. Yours may be named just vw_Tabs if you didn't install with a DB prefix.

I replaced

dbo.dnn_RemoveStringCharacters(TabName, '&? ')

with

REPLACE(REPLACE(REPLACE(TabName,'&',''),'?',''),' ','')

in the 2 places that it occurred and updated the view. It is MUCH faster!

I benched these 2 for 1000 iterations each:

declare @i int;
declare @s varchar(255);
set @i = 0

while @i < 1000 begin
  select @s = REPLACE(REPLACE(REPLACE(TabName,'&',''),'?',''),' ','') from dnn_Tabs
  set @i = @i + 1
end


set @i = 0
while @i < 1000 begin
  select @s = dbo.dnn_RemoveStringCharacters(TabName, '&? ') from dnn_Tabs
  set @i = @i + 1
end

UDF took 2:59 for me

nested replace took just 0:18