low performance with highgui

[1mZ1kk4d0]

I recently included in my project the use of opencv together with scap to generate a preview of the screen, however note that the use of highgui with the name leaves it with a meaningless accumulation of memory, I would like to know if this is my error or if It's a lib error.

Example
https://youtu.be/i9HIsh-yEM8