If your scene contains more high resolution textures than your video card has enough memory to handle, textures may appear blurry or fail to load in the Viewport. This is a sign that Clamp Texture Resolution is enabled and working. To work around this, see Troubleshoot "Blurry textures or GPU texture ram exceeded, texture loading failed" error message
In addition, you can select among different texture loading modes in the Display section of the Preferences window. Select Immediate mode for the fastest scene loading time; however, you may have to wait briefly before you can interact with your scene. Alternatively, you can select Parallel mode so that you can interact with your scene while materials realize and textures load. See Display preferences.