Although each TreePad article has a maximum size of 1 Mb (approximately one million characters), there is no set limit to the size of an entire Treepad file.
In general, TreePad Lite files of up to 20 Mb and/or 2000 nodes are safe to use. If your document exceeds these parameters, we recommend you split it by exporting a large node to a separate file, then deleting that node from your original document. See also "node://TreePad Lite Manual/TreePad Lite reference/The tree/Splitting and joining files"
Occasionally, the Windows operating system can limit the size of an article to about 16000 characters. This is caused by running certain 16-bit (Windows 3.x) programs before you run TreePad or some faulty dll's have been installed on your system by other applications.