After New RAM, Slower Initially

I recently upgraded by MacBook with 2 matched 1GB sticks of Corsair RAM and boy, does it make a difference...after a while.
When I start up the computer, it's now slower than it was with the 512mb of stock memory. However, after running a few programs (which also take longer to startup than before - Firefox takes between 40 and 50 seconds to start), the computer speeds up quite a bit. It really flies - Word opens in less than 1/3 the time.
Is there something I should have done in software to allow better allocation of the RAM? Is this normal? If not, what can I do about it?


How long is "after a while?" I ask because I'm thinking about getting an upgrade, but I'm wondering if it's worth it. I can't be sure, but I would assume it has to do with the fact that the RAM sticks haven't been used before, but don't trust me, I have never done this. Does it do this with all of your apps or just a few? How long does it last?