PCL means printer control language and PS means postscript.
Printer control language (PCL) was released in the 1980s by Hewlett-Packard as a simpler, faster and less expensive alternative to PostScript-based laser printers.
PCL driver enables access to the maximum number of printer features, it offers limited capabilities. However, for everyday office color printing, this driver is recommended.
If you are printing color graphics or are performing desktop publishing, PS (PostScript) driver is recommended. Ideal for both Mac and Windows, this driver produces the most accurate color output.
This autotuning fix is definately something to try if you are experiencing slow network/internet speeds in Vista / Windows 7 or 2008 server.
How do you run this fix:
To turn off autotuning launch a command prompt as an Administrator (type “cmd” into the Start box, right click on Command Prompt and select “Run as Administrator), then enter the following line:
netsh interface tcp set global autotuning=disabled
Restart your pc after running this command.
If you want to set this back to normal type the following:
netsh interface tcp set global autotuning=normal
Here is a link for more information regarding autotuning from Microsoft.