swap ( page faults ) always happen on windows even though there are lot of free RAM available on the machine. windows chooses to use swap all the time and this does not cause any slow down . what makes the process choke or become slower is the hard fault or major page fault
on linux the behavior is different . It does not use swap unless the machine is running out of memory.
in the attached screenshot as you can see that all processes on the box have page faults but there is no major fault and there is 2 GB free RAM on the machine
to reproduce you can reboot the box , install couchbase and start running memcachetest load against the node.
you will see that swap usage increases from 100MB to 1 GB . there are many page faults which is fine and there is no major faults ( hard fault)
when free RAM is less than 100 MB and swap usage is near RAM there is 40 hard faults per second