It sounds (pardon the pun)as (1)You either do not have enough memory,(2) The machine is not powerful enough for the upgraded software,(3) It is very fragmented, (4) the hard drive is full,(5)The machine is running hot, causing the processor to run slower, (6)the paging file is set incorrectly.
To get to paging file (memory), do the following:
Press the windows key and the Break key together,Select advanced,Select Performance, then advanced, and finally Virtual memory. change to let window decide,and click set. You will need to re-start your machine.
Hope this helps