I asked about this recently but now I have a different situation.
My laptop has max 16GB and I recently purchased two sticks of 4GB RAM.
I already have 6GB ram in the form of 4Gb and 2Gb.
I have 2 slots which accept 8Gb each.
What I need to know is that can I dual channel with 6GB in one slot and the two 8GB sticks in the other slot?
On a laptop there's not going to be any discernible differences, but the more 'RAM' you have the longer it takes to wake from Hybrid Sleep or Hibernation -- and IF you have an SSD then the larger the Page File and the S4 file size.
IF you really want to speed things up then IMO get an SSD -- much faster performance and increased battery life -- waking is considerably faster -- no moving parts to be damaged -- etc. An SSD is a Notebooks best friend.