Printer's "paper per minute" speed dropped

Hi, does anyone encounter this before? Usually my office use to print out some daily transaction records via a networked HP Laserjet 5100, the document is just 51k excel with 3 page of black & white number figures, the HP usually takes less than 15sec. to print out all docs. but lately it seems the printing process on the printer was dropped.
The printer prints very slow nowadays, i assume from around 40ppm drops to around 20ppm (paper per minutes) so is that means is time to service the printer?
Hope to have some advice from experts like u guys!! :)