This code runs sometimes in less than one second, but sometimes its very slow???
(system info)
Would this be quicker as a shell command?
do shell script "system_profiler"
This may take a while to run but will return everything you may need to know about your system.
You could also try
system_profiler SPHardwareDataType
or
system_profiler SPNetworkDataType
etc…, as a do shell script to narrow your results (and make it quicker!!)