Fix Huge PDF Print Spool Files and Slow Plotter Printing
Question details
A small PDF file generates an unusually large print spool file when sent to a plotter, resulting in extremely slow printing speeds on large paper sizes.
- Product
- PDF Editor
- Device & OS
- not provided
- Scenario
- Sending a PDF file containing complex CAD drawings or transparencies to a large format printer or plotter.
- Observed behavior
- The print job in the spooler expands to a massive size—often hundreds of times larger than the original PDF—significantly slowing down or failing the printing process.
Before proceeding, determine if the issue occurs with all PDFs or only specific files, such as complex CAD exports. Ensuring your printer or plotter has the latest driver directly from the manufacturer's website is also a critical first step.
Disable the Print as Image Setting
Turning off the "Print as Image" option prevents the PDF from being rasterized into a massive bitmap file before printing.
When 'Print as Image' is enabled, the PDF software renders the entire document into a single large image on your computer before sending it to the printer. While this is useful as a temporary troubleshooting step for specific printer errors, leaving it on permanently will cause spool files to balloon in size, particularly for large formats like A1.
Open your PDF file and click on 'File' > 'Print', or press Ctrl+P on your keyboard.
In the Print dialog box, locate and click on the 'Advanced' button, typically found near the top or bottom of the window.
Find the 'Print as Image' checkbox within the Advanced Print Setup menu and ensure it is unchecked.
Click 'OK' to save the advanced settings, then click 'Print' to send the document to the plotter normally.
Flatten Complex CAD Content and Transparencies
Flattening overlapping elements and CAD transparencies simplifies the file data sent to the printer driver.
Configure Printer Driver Rasterization Settings
Adjusting how the specific printer driver handles vector data can significantly reduce the processed print job size.
Print Large PDFs Seamlessly with WPS Office
WPS Office features a lightweight and highly optimized PDF reader designed to handle complex documents with ease. Its intelligent printing engine ensures that your print jobs remain fast and manageable, offering a smooth printing experience without overloading your system's print spooler.
- 1. Download and install: Download and install WPS Office for free from the official website.
- 2. Open the PDF: Launch WPS Office and open your large or complex PDF document using the built-in PDF tool.
- 3. Access the print menu: Press Ctrl+P or go to Menu > Print to open the print dialog box.
- 4. Select the plotter: Choose your large-format printer or plotter from the drop-down printer list.
- 5. Print efficiently: Click 'Print' to send an optimized, cleanly formatted print job directly to the spooler without unnecessary bloat.
Frequently Asked Questions
Why does a 2MB PDF turn into a 2GB spool file?
This happens because the printer driver or PDF software rasterizes the vector data into an uncompressed raw bitmap image. Since large paper sizes (like A1 or A0) require extremely high resolutions to print sharply, the resulting image file becomes massively bloated compared to the original compressed vector PDF.
What does the Print as Image setting actually do?
The 'Print as Image' setting bypasses the printer's internal vector processing. Instead, your computer calculates exactly what the page looks like pixel by pixel and sends it to the printer as one giant picture. While it helps bypass rendering errors caused by faulty printer drivers, it consumes vastly more memory and spooler space.
Can CAD layers and transparencies affect PDF print speeds?
Yes. When complex CAD drawings export to PDF, they often contain thousands of overlapping lines and transparency effects. The printer spooler has to calculate the visibility and rendering of every single object before printing, which drastically increases the spool file size and slows down the processing time.
