Mid-2014 rMBP -- integrated card performs better than discrete?

Hey all,

Complete mac newb here--purchased my rMBP about 3 months ago. For the most part, it's been fantastic--but as of the last several days, I've noticed a strange disparity re: graphics performance. When I'm using the nVidia card (usually in conjunction with Maya, Photoshop, etc.), I'll experience lag in strange places (particularly UI elements such as opening apps/windows and the "fan" effect of the Dock download shortcut). Not quite sure how I'm getting these symptoms of system taxation with 16GB of RAM. Furthermore, the graphics-switching system has been fiddly as of late--sometimes, the discrete card will stay in use after I've closed the applications that typically activate it (rectified only by a restart). I recently updated to 10.10.3, but these symptoms started surfacing only *several* days after the installation--is there any chance they *could* be related? Or should I play it safe and head to an Apple Store for diagnosis (as obviously, I'm still under warranty)?

Thanks in advance.