1. Is the slowdown in all files or just one? Start a new drawing by typing .new and see if the resulting file is ok or not. If ok then the existing file is the problem. Run Recover on that file to see if that helps, see other tips further down.
2. Once a slow drawing up checks to see what fonts are being used or called. If you don't have one on your system substitute in STYLE for an AutoCAD shx font. Do this for other font names you don't recognize to see if the bits of help speed up the drawing. Change all TTF fonts to SHX to see what difference it might make.
3. Does the drawing contain XREF files? Close the current drawing, open each XREF file and audit and purge each one. Then go back to your drawing. In 2010 you can use the RECOVERALL command to also include XREFs.
4. Check-in layer manager to make sure you don't have 100's of layer filters if so delete them.
5. Check the scale list to make sure you don't have 100's of scale lists. 2009 and higher does this for you automatically, 2008 use scalelistedit, reset. Use Scale List Cleanup Utility
6. Change ALL text styles to use simplex.shx font as a test, but jot down what font is used with each style. Try QTEXT on as well to test speed. If one of these helps then you have narrowed down the problem to a text font. Add them back one at a time to find the trouble one.
7. Don't use true type fonts (TTF) and see if that helps, lots of those will slow things down. If using TTF, turn hardware acceleration off.
8. Set Shademode to 2D, do this in each layout, each viewport, and in Model Space.
9. Use -purge, Regapps, purge all. In 2010 and higher also use –purge, z (zero length geometry), and –purge, e (empty text object), -purge, g (groups).
10. Go to File>Open>History, are there hundreds or thousands of files listed? Delete most of those shortcuts keeping only the last 20 or so.
11. Properties will cause slower operating speed and some have recommended setting qpmode to 0(off). Run with Properties turned off as well as QProperties off as a test.
12. Options> Open and Save > Turn off display digital signature information.
13. Dock the command line in the lower or upper portion of the AutoCAD screen, do not have it floating. If the command line is not showing it can still have an impact if it was floating prior to being made invisible. Hit Ctrl+9 to bring it back, if it is floating then dock it at the bottom of the AutoCAD screen, then hit Ctrl+9 again.
14. Set ltscale to the proper value, a large drawing with linetypes will slow down when in MS with ltscale set to 1 or a small value.
15. Go to autodesk.com web site, pick Services and Support, use the Knowledge Base and search on "slow", "delay", etc.
16. Use Cleanscreen (CTRL+0 toggles it off and on) to remove all palettes, etc. and see if it makes a difference.
18. Turn transparency off on tool palettes. Hover over a palette and right-click, pick transparency,...
19. If you don't need draw order then set draworderctl to 0.
20. Turn DYNamic input off as a test, see DYN toggle at the bottom centre of the screen.
