First, if you haven't already, go here and download the full featured driver package for your printer and your specific version of Windows 7 (x86, x64). It supposedly address an issue with slow printing. HP also recommends that if you have a previous version of the software installed, that you uninstall it prior to installing the new version.
Other than that, you can always attempt experimenting with some of the driver properties. Try changing some of the spool features by changing it to print directly to printer, try adjusting some of the advanced features like disable/enable bi-directional printing. If nothing helps return the settings to their original parameters.
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