A naive way to split a PDF would be to render each page to an image and paste those images into new documents, the same approach a screenshot-and-reassemble tool would take. That approach quietly throws away selectable text, shrinks image resolution to whatever the render happened to use, and bloats the file. This tool does not do that.
Instead, each page in a PDF is its own object in the file, referencing its own content stream, fonts and images. Splitting means copying the page objects you selected directly into a brand new document's object graph, the same operation a desktop PDF editor performs internally. Nothing is decoded to pixels and re-encoded, so text stays selectable, fonts stay embedded, and images keep their exact original resolution and compression, whether you are pulling out a single page or a large chunk of the document.
If you need to go the other direction afterward, Merge PDF combines files back into one document using the same page-copying approach, so a document split into pieces and merged again is identical to the original. And if the split files are still larger than you would like, Compress PDF Images can shrink their embedded photos afterward without touching text or layout.
