What would cause a webapp to run slowly only on computers within our network? [on hold]

We host a web app in-house and it runs great outside of the office - no issues with load time. While running it internally/in-house, however, the web app runs very slowly on computers that are wired in through ethernet cables. This is only a problem with the desktops that get internet through ethernet cables, not any computers that access it via wifi. It could take almost a minute

Is there some kind of setting that could make the web app run so slowly? There are no issues with any other sites on the desktop computers and they have high internet speeds as well.