When I put my computer together, I installed 8 gig of RAM. Sometimes it isn't enough. With Kontakt, there's something you can do to help reduce the memory required for an instrument.
I read this on a website and cannot find the website to give the author credit. I'm sure it's common knowledge for those who read manuals :-) I pass it on for what it's worth.
Load any instrument you want to use. After everything loads, look under the name of the instrument and you'll see Output, Voice, Max and Purge. Purge is a dropdown menu. Below voice is the Memory size of the instrument.
Now click the down arrow to the right of Purge and select "purge all samples."
Look at the memory size now.
Now play one note. The memory size will increase, reflecting the size of the sample the note uses. You can see whenever you play a note that requires another sample. You may also see different samples at different velocities on the same note.
How is this going to help reduce memory usage for a lot of instruments?
Look at the menu bar at the top of Kontakt. Toward the right is Purge. This purge will affect all loaded instruments.
The idea is that as you add instruments to a song, you can use purge and let your playback cause Kontakt to load only the note samples necessary for that song. If you write a part that only uses a few notes, why have unused note samples in memory?
If I'm having trouble getting a sequence to play smoothly, rather than freeze a track where I cannot edit it, I use purge. I play the sequence through once to make sure the samples it uses are ready to play. When I play the sequence from then on, it usually plays without any glitches.
Hope this helps someone. It helped me :-)