At our office we've faced this problem as well as some clients asked us about slow performance printing PDF files through one our products.
After a new coorporative printer/drivers deploy, end users complaint about very slow printing when they print PDF medium size files and terribly slowness with large files.
Why it happens:
After a bit googling we can find some articles like this http://www.laserquipt.com/support/idx/0/063/article/PCL-vs-Postscript.html when they explain the diferences between the 2 major printing protocols PCL and PS here are the description, pros and cons:
PCLPrinter Control Language or PCL is a common printing language used widely by many different printer manufacturers. PCL is supported by many different Operating Systems which allows for the same printer to work in many different environments. PCL is device dependent. This means that the drivers for this language utilize the printer hardware for creating some of the printed data, usually graphics data such as fill areas, underlines or fonts. This allows the computer to process the print job quickly and efficiently. The printer is then responsible to complete the creation and processing of page data. Individual printers may perform these tasks differently giving you a slightly different output.Pros:Fast print processing.Widely supported in many different Operating System platforms.Cons:The same print job on two different printers may vary slightly.Quality of graphics is dependent on the print device.Not supported in most Macintosh environmentsPostScript:Postscript language or PS is a common printing language also used widely by many different printer manufacturer. It is used heavily in Macintosh platforms and for graphic applications in several platforms. Unlike PCL, Postscript is device independent. This means that the Postscript language creates all of the print data and does not rely on the printer for print data. This allow the output to be consistent when printed on more than one type of printer or print device. Specifically, the graphic objects will be consistent and in some cases of higher quality than PCL.Pros:Graphical objects are often more detailedThe same print file should print identically on two or more different print devices. (This most beneficial when used for printing drafts on one printer then sending out to a printing company for production)Cons:Print processing can be slowNot found in as many platforms as PCLPrint file and memory requirements are larger.
Another good explanation can be found here http://community.spiceworks.com/topic/115306-postscript-vs-pcl-windows-7-and-hp-universal-driver
For example a vector graphics package like Quark, or Adobe Illustrator. Adobe Reader can usually work with PCL drivers just fine without much impact to performance. Unless you output some very large PDFs you won't notice a difference, but it depends on the enviroment, particularly on the printer. The thing to bear in mind with PostScript is that during printing the vector image is converted to raster in a process called RIP, or raster image processing. HP printers handle this at the printer on the fly with a built-in RIP. Other printers do this on the PC with the driver handling the RIP, or may have an emulated RIP. A RIP (non-emulated) on the printer is typically faster as the OS is freed up to just send the raw print job without pre-processing. Postscript drivers are generally best suited for printers that have built in RIPs that can handle postscript natively.
Finally we can check the driver recommendation table from lexmark support that helps to see it clearly organized by application/content here http://support.lexmark.com/index?page=content&clearQuestion=Y&id=FA787&locale=en&userlocale=EN_US&segment=SUPPORT&productCode=
As we understand from the refered links there is not a magic formula and it depends on the printer specs and the end users printing contents, maybe you have users that will work fine with PS drivers and others with PCL and maybe you have to set up two printers, once associated with each driver, on those users with more demanding printing requirements and explain to them which one is the best suitable for an specific content.