Set the Ancestor Limit for History Trees
How do I limit the number of ancestors that can be present in a file history tree?
By default, a SnapGene sequence file embeds all of the ancestral sequences that contributed to the current construct. Those ancestral sequences can be viewed and restored using History view. Extensive history trees can result in large SnapGene files. To limit the potential size of SnapGene files, set an "ancestor limit".
Click SnapGene → Preferences (macOS) or Edit → Preferences (Windows or Linux), and select "Files" in the sidebar.
Use the drop-down menu to choose the maximum number of levels in the history tree, or type to enter a specific number. Then check the box to "Limit file history trees".