Max Shutter speed
Canon 90D can shoot continuously at max speed of
11.0 fps and has max shutter speed of
1/8000 sec. 90D also has an electronic shutter which can shoot silently at max speed of
1/16000s. One thing to keep in mind is that electronic shutter may cause rolling shutter / jello effects, and also banding issues under artificial light on your images.
Flash
90D has a built-in flash, and it also has a flash shoe to mount your external flashes too.
Focusing
Canon 90D features both Contrast Detection and Phase Detection autofocus (AF) systems which ensures speed and accuracy of focusing in most situations. The AF system has 45 focus points and 45 of these sensors are of Cross-type. Cross-type sensors locks focus faster and more accurate compared to single type sensors. Canon 90D also features
Face detection AF where it intelligently detects the faces in the frame and locks the focus automatically.