Update buffered graphical statements, drawing them to the selected canvas target.
Windows usually runs with time slices of about 15 to 16msec (64Hz).
When you do Canvas_Redraw (or any other Canvas update of the visible window on the screen) then the update is done and the remainder of the time slice is handed back to the operating system even though you could do other actions with it.Since you update your screen after each data item you will then be limited to incoming data at the time slice rate of 64Hz.
The quick fix is to tell Windows to reduce the time slice to a minimum. It will usually reduce it to 1 or 2 msec.