These two threads might interest you:
https://vborg.vbsupport.ru/showthread.php?t=104657
https://vborg.vbsupport.ru/showthread.php?t=137086
There is obviously going to be a greater impact (Although insignificant) on performance when using plugins over actual edits to a file; though this can be avoided by not using large amounts of code in plugins - or including a file (as seen in the first link) that contains the code being executed, rather than having it executed directly from the plugin.