It sounds like you have more than enough power: http://ni.com/labview/requirements.htm although it could be the OS...
Did you just replace the top level L-M vi's or all of them? Like I said, the majority of the changes appeared to be buried in the lowest level subvis. You may want to try using the vi profiler to see where the majority of the time is being spent and isolate that vi. (Tools->advanced->Profile vis... at least in LV 6.1 I'm not at a station w/ LV7 presently). You'll want to select Timing details. See if any vi is running a long time or an excessive amount of calls and compare this vi to the LV6 version. If it's different, replace w/ the LV6 version. If it still slogs... hmmmm... maybe format and do a clean LV7 install? :) Lemme know what happens, since I use L-M frequently... just not in LV7 yet.
