I wouldn't consider myself a powerlifter. Most of my exercises are in the higher rep range, but I like to be explosive with my main compounds.
And yeah, sluggish is a good way to put it. Like earlier this week when I went to bench, each rep was very slow, but I wasn't sticking at any point. Normally I get the weight up very quickly. Each set probably took an extra 10-15 seconds to complete. Basically it was like I was benching in slow motion.
Could be joints; sometimes I get a mild stiffness the morning after training. Which sucks because I'm actually taking supps for joints... I might just lower the weight and increase volume for now.