When the sluggishness and spinning happens, please optn a terminal (Apps->Utils->Terminal) and type:
sudo spindump
This will measure what is happening and create a file. Please send me that file, by typing open <<filename>
Eg:
osx:~ jeremylaurenson$ sudo spindump
WARNING: Improper use of the sudo command could lead to data loss
or the deletion of important system files. Please double-check your
typing when using sudo. Type "man sudo" for more information.
To proceed, enter your password, or type Ctrl-C to abort.
Password:
Sampling all processes for 10 seconds with 10 milliseconds of run time between samples
Sampling completed, processing symbols...
Spindump analysis written to file /tmp/spindump.txt
osx:~ jeremylaurenson$ open /tmp/spindump.txt