Slow CAD System. Slow Drawings.


  • Why is my CAD system slow?
  • How can I speed up my CAD file?
  • What causes CAD drawings to run slow?


Here is a list of things that can slow your system down:



  1. The use of Pattern-Fill planes that contain a large number of small lines e.g. grass. This is the BIGGEST issue affecting speed. (V8 overcomes this to a large extent but it is still relevant)
  2. Having Pattern-Fill planes set too small (wrong Plane scale value) causing too many repeats of the pattern to fill the area. This can also crash the system as it runs out of memory. (V8 overcomes this to a large extent)
  3. Transparency. Transparent planes rely on the graphics card and Open-GL to display. If your graphics card is not ideal for this work then speed issues will occur
  4. Gradient Fill with the spacing set too small. The larger the area the larger the spacing should be set
  5. Bitmap Fill of large areas with the bitmap fill size set too small causing too many repeats.
  6. Pattern-fills or bitmap-fill loading across a network from a server machine instead of from the local hard drive



  1. Large volume of text in a drawing will affect speed. Text is notoriously complex for CAD to process accurately so it takes time.
  2. Complex fonts with jagged edges to emulate hand drawn looks are often hundreds of times slower than simple fonts. Use the most simple font your ‘style police’ will allow. Or switch from one style to another before printing.



  1. Too many components, especially if they are complex detailed ones. Be careful not to pick detailed components which, when printed will be too small to see the detail of anyway. Some things that look good on screen don’t look as good on paper.
  2. Nested components. I.e. components inside components inside components. Often happens with files you import from AutoCAD.
  3. Components loading across a network instead of from the local hard drive

Remember that a component is a drawing unto itself and each one can contain a great number of entities. For LANDWorksCAD users, switching between simple, detailed and Image plants can make a big difference.



  1. Groups are an entity in their own right so they tend to add to the number of entities in the entire drawing that has to be processed by the display. Keep Groups to a minimum.



  1. Too many views open. Every open view has to be displayed and refreshed, so the more view windows you have open the slower the system becomes.
  2. Layout views are slower than model views as they use a different method of displaying the information. Try to use a single model view such as a Top view most of the time


Multiple Apps

  1. Having more than one session of your software running at the same time will take much or your system memory. Consider increasing your system AM or only having on session of your software open at a time.


Line Weight

  1. Ticking the option to display weights makes the drawing look more real but adds to the calculation required to display. This is usually a minimal issue but does contribute overall.


Line Styles

  1. If you’ve imported a drawing from a DWG or DXF file it may contain dashed line styles that look fine n their system but are way to ‘fine’ on yours so there are millions of dashes to calculate instead of just a few hundred for each line!. Check you have the View Scale set large enough or consider changing all entities to a solid line style to see what effect that has.


Wrong View Scale

  1. If you have your view/print scale set too close to 1:1 and the file is designed to be printed at say 1:200 then dashed lines and hatching (and even some text) will have to work 200 x harder to calculate how to display. Try changing the print scale to see if that helps.


System Default Settings

  1. Display Tolerance’ set too small (less than 2) This effects the display of curves and arcs etc. Too large makes circles look like hexagons. Typically keep between 2 and 8.
  2. ‘Reduce Detail for Pan and Zoom’ option unchecked (not really such an issue for v8)


Multiple Copies

  1. Accidentally making copies of entities, either on top of each other or off into space. The software has to think about all the lines in your model, not just the ones you can see.


Image files

  1. Images can often be very large files and this can take up quite a bit of your systems memory. Consider using smaller image files. (less of an issue in v8)


Imported files

  1. Files that have been imported from other CAD systems may bring with them unwanted and even unseen entities and settings that do not benefit you. We have seen some imported files, that look simple, but are 50 times slower than the same information created directly in RealCAD/LANDWorksCAD etc. Copy and paste the entities from the imported file into a new clean file before adding your new entities.


Your Computer

  1. Not enough RAM. We would regard 16Gb of RAM as the minimum for commercial use.
  2. Poor Graphics Card. A built in, non-dedicated graphics card is no good for CAD. Be sure to have a powerful Graphics card that supports Open-Gl and has plenty of RAM.
  3. Slow Hard Drive. Old hard drives are slow. Make sure that you have an SSD (solid state drive) these have no moving parts and can load and reload information fast.
  4. High resolution monitors make your drawings look great and prevent you from having to zoom in and out so much. The trade-off is that they require more processing power to display because there are more pixels.
  5. Wrong CPU. If you haven’t got a fast CPU then all else will fail. It doesn’t have to be multicore as this won’t help. Just get a fast simple CPU such as an i7 (i5’s tend to be much slower) By the time you read this a new one may also be available!


Working methods such as switching layers and planes on and off as required can be a big help in work flow management.