As a first step, let's see if the following can help improve the performance:

  • Try clearing user temp directories. Revit uses this directory and when it becomes too full, Revit performance can be impacted. First close Revit and your other applications. Then in Windows File Explorer, type %TEMP% for the path. Select all and delete: 
    • C:\Users\<user>\AppData\Local\Temp
    • C:\Windows\Temp
    • C:\Temp
  • If you are currently working in Revit, sync, relinquish and close all sessions of Revit.
  • Empty your trash. 
  • Reboot your computer.

If the issue persists, please try the following: 

  1. Open each model with the Detach from Central and Audit boxes checked. Purge each model at least 3 times to clear all unused elements (sometimes a 4th purge is needed).
  2. Re-save the cleaned-up models as new centrals. Users should delete their existing locals and the backup folder of the same name. (It's a best practice to create a new local each time the model is opened.)
  3. Remove any unnecessary or outdated Revit and CAD links. Linked files from other sources (CAD or IFC for example), can lead to performance issues. 
    • When working with a project that uses worksharing, place model imports in a new workset, which by default is not visible in other views.
    • Avoid exploding *.dwg files in Revit. This will minimize the file size and save time when linking. (Note: In some cases it's necessary to explode *.dwg files in AutoCAD if some elements are not visible when the file is linked to Revit).
    • When linking large *.dwg files (over 1 MB), remove any unnecessary data, such as large hatch patterns, and only use the information that is actually needed in Revit.
    • Make sure that the linked file does not use large coordinates. This can be done by checking the origin of the *.dwg file prior to importing, and moving the drawing elements closer to the file's origin if necessary.
    • If the *.dwg file contains xrefs, bind them to the host file before linking the *.dwg to Revit. 
    • If working with site plans with proxy objects, export the file to AutoCAD format to convert all proxy objects.
    • Before linking the *.dwgfile into Revit:  
      • Open it in AutoCAD, and purge and audit the file
      • Change proxygraphics to 1
      • Change all text to Arial (Revit cannot read line-based fonts such as RomanS).