2015 MBP 13" always pokey with PDFs?

Hi everyone,

I've been a 15" MBP user since they launched in 2006, but I recently got an early 2015 13" (3.1 GHz core i7) with 16 gigs of RAM and the default integrated Intel Iris Graphics 6100 graphics card, which I gather shares system memory. I don't work in graphic design; I'm an academic, but I like to have lots of article PDFs open, and I like to have lots of programs open. I'm coming off a 15" MBP mid-2010, whose dynamic switching started causes panics due to that infamous GPU problem.

I've been startled to see the system get all pokey with just a bunch of PDFs open. No crashes, but everything seems labored. Has anybody else noticed this kind of behavior? Is it the price one pays with the less robust graphics card? I may just tough it out, because I love having a smaller machine, but it's pretty irritating when all I'm doing is looking at image files.