High Scoring Lines Causing Slowdown on PS4

I've been grinding out score for the crew bounties and I usually just chill out in a half pipe or bowl because it's easier for me to keep the multiplier going. Every time I get to around 30k line score, the game starts to slow down. I got to 200k line score and it was like I was moving at nearly half speed. As soon as I decided to let the multiplier timer run out, it went back to full speed. Got back up to 30k line score and I noticed it starting to slow down again.