Issue Description
Project file size is noticeably larger than expected, often exceeding 1 GB. You experience slow opening and saving, lag during navigation and editing, and frequent freezing or delays when switching views, creating elements, or accessing the layout book.
There is not a particular size of file which is ideal, however, keeping your files as small as possible is recommended. As of 2025 we typically see PLN file sizes range between 100MB to 1 GB. If your PLN file is around 1 GB or more, we strongly suggest you check your file for any areas you can optimize.
Solution
There are some key areas you can look in order to clean up and shrink a file's size.
Embedded Library Objects
To check the Embedded Library, go to File > Libraries and Objects > Library Manager or just File > Library Manager, double click on Embedded Library and highlight individual objects in the list. You will see their size identified. Poorly scripted objects can be bloated. If you see any parts more than a few MB in size, consider replacing those objects with better scripted ones. Most objects will be in the range of a few hundred Kb or less.
Delete Layouts
Make a copy of the PLN file for testing. In the test copy, if you delete all layouts except for a single empty layout, then re-save the PLN file, note the new size of the PLN. If the file size decreases significantly, this is expected. The Layout Book typically contains more instance-based elements such as notes and 2D elements, which causes Archicad to store a large amount of data in the file. If this is the case and is causing performance issues, there are ways to split the Layout Book and the source model into separate files. While this method has its own trade-offs, it is utilized widely in case of project with high complexity. See a case study that demonstrates the process.
2D Elements
Lastly, check for a large number of 2D elements like lines, arcs, polylines, splines etc in the project. Although it may seem counter-intuitive, 2D elements cause more file bloat than many 3D objects. Tools like the Line tool, Polyline tool, Arc/Circle tool are instance-based, meaning that they are defined directly in the workspace. A GDL object or construction element, by contrast, is scripted and re-uses a lot of parametric scripts to keep the elements' impact on the file smaller.
Here are helpful articles we have related to file size:
How to Optimize Your Project Performance