PNotes is described as '(Pinned Notes or Portable Notes, use what you prefer) is written entirely in C and Windows API (with Pelles C for Windows IDE) - so it is fast and light-weight. It has flexible settings - both for the program in whole and for individual note' and is an app in the Office & Productivity category. There are more than 100 alternatives to PNotes for a variety of platforms, including Windows, Android, Online / Web-based, Mac and iPhone. The best alternative is Joplin. It's not free, so if you're looking for a free alternative, you could try Standard Notes or Microsoft OneNote. Other great apps like PNotes are Evernote (Freemium), CherryTree (Free, Open Source), NoteLedge (Paid) and Trilium Notes (Free, Open Source).
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.